Cogeneration and Energy Savings in a Food Processing ...

Cogeneration and Energy Savings in a Food Processing Industry: Case of Juaben Oils Mills (Ghana)


Thesis written by Félicien D. BADOU/ 37th Promotion 2iE - June 2008

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• To the Omnipresent, the Almighty, the Omniscient and

the Merciful GOD, for His divine assistance,

• To my late father, Marcel Dossa BADOU whose

maxims are still fresh in my mind and make of me a

man,

• To my beloved mother Micheline TOGNON for her so

wonderful love, her affection, tenderness and daily

prayers,

• To my uncle and adoptive father Louis BADOU and his

Wife for the warmth of which they surrounded my

teenage,

• To my brothers and to my youngest sister Christèle

BADOU for their cares and moral supports,

• To the current and to the future promoters of

Cogeneration for a best future of the Humanity Cradle,

I dedicate this final project.

DEDICATION



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ACKNOWLEDMENTS

I first of all would like to express my heartfelt thanksgiving to GOD for the vital breath

and for the health He has bestowed on me during this assignment.

Carrying out this project has been possible thanks to the multiform contribution of many persons.

From the bottom of my heart, I expressed to them my gratitude through the following lines.

To my supervisors: Professor Yezouma COULIBALY (2iE) and Mr. Emmanuel W. RAMDE

(MED, KNUST) who entrusted to me this important work on Cogeneration. Despite their busy

schedules, they found out time to guide me with insight. I am profoundly indebted to them for

their expert suggestions and for pushing me further, even when I thought I have given my best.

A big thank you to Madam Susan STRAND, whom with my supervisors allowed me to

complete my final project in Kumasi. It is an untold and invaluable present you offered to me to

edit my memoir in English.

My gratitude to Doctor ANSONG, Head of the Mechanical Engineering Department (KNUST)

for the precious advices he gave to me when I visited him and especially for the remarks done on

my work during the “Master of Science Seminar” we held.

I don’t have the appropriate words to express my thanks to Professor AWUAH, Dean of the

College of Engineering. Your motherly welcome when I met you in KNUST and your kindness

which opened to me the door of the laboratory of the Civil Engineering Department for my

experiments are ever fresh in my heart.

I am thankful to the Managing Director of Juaben Oils Mills who has accepted that I conduct my

project in his mills. Special thanks to Mr. Philip ADJEM, the Technical Manager of the mills.

Dear Sir your assistance and help have been very determinative to this project.

I also would like to thank these kind technicians who helped me for the experiments and

measurements I did during the project in particular the Sirs Opoku, Donkor, Botehway,

Kingsley, “Teacher”, Bansah, Anoutché, Yaw, Pius, Francis, Frimpong, Charles, Ben and

Maxwell.

Thanks to Mr. BAGRE who warmly supported me for my researches on Internet.

Infinitely thanks to the student family of 2iE, to my compatriots of 2iE and to the Beninese

medical student of the University of Ouagadougou, to my brothers of Rotonde, to my friends of

“Ardent Bush” and of “Eucharistic Movement of the Young”. Thanks for the brotherly love of

which you surrounded me at the time of my accident and of my surgical intervention.

I owe to all of you a priceless debt that only GOD can repay. May He bless you abundantly



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ACRONYMS

Ag2SO4: Silver sulphate

ASEAN: Association of South East Asian Nations

BOD5: Biochemical Oxygen demand after 5 days.

CED: Civil Engineering Department (KNUST)

CHP: Combined Heat and Power

COD: Chemical Oxygen Demand

CPO: Crude Palm Oil

ECG: Electricity Company of Ghana

EDF: Electricité de France (in English Electricity of France)

EFB: Empty Fruit Bunch

FAO: Food and Agriculture Organization

Fe2(NH4)2SO4.6H2O: Di-ammonium iron II sulphate

FFB: Full Fruit Bunch/ Fresh Fruit Bunch

FHT : Francs Hors Tax (in English Exclusive of Tax)

GCV: Gross Calorific Value

GDP: Gross Domestic Product

GJ: Giga-Joule

H2SO4: Sulphuric acid

JOM : Juaben Oils Mill

K2Cr2O7: Potassium dichromate

KNUST: Kwame Nkrumah University of Science and Technology

LHV: Lower Heating Value

MED : Mechanical Engineering Department (KNUST)

MnSO4: Maganous sulphate

Mt : Metric tons

MW : Megawatt

Na2SO3: Sodium thiosulphate

PKO: Palm Kernel Oil

POME: Palm Oil Mill Effluent

SB: Shea Butter



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CONTENT

DEDICATION ................................................................................................................................ ii

ACKNOWLEDMENTS ................................................................................................................. iii

ACRONYMS ................................................................................................................................. iv

LIST OF FIGURES ......................................................................................................................... 3

LIST OF TABLES .......................................................................................................................... 4

INTRODUCTION ........................................................................................................................... 5

Chapter I: BACKGROUND ............................................................................................................ 6

I. PANORAMIC VIEW ON COGENERATION ....................................................................... 6

I.1. Definition .......................................................................................................................... 6

I.2. Types of cogeneration ....................................................................................................... 7

I.2.1. Cogeneration with engines ........................................................................................ 7

I.2.2. Cogeneration with gas turbines ................................................................................. 7

I.2.3. Cogeneration with steam turbines ............................................................................. 8

I.2.4. Cogeneration with the combined cycle ...................................................................... 9

I.2.5. Cogeneration with fuel cells ...................................................................................... 9

I.3. Impacts of Cogeneration ................................................................................................... 9

I.3.1. Energy impact ............................................................................................................ 9

I.3.2. Economical impact ................................................................................................... 10

I.3.3. Environmental impact .............................................................................................. 11

I.3.4. Impact on electricity distribution grid ..................................................................... 11

I.4. Practice of cogeneration throughout the world ............................................................... 11

II. AVAILABILITY OF BIOMASS FROM FOOD PROCESSING INDUSTRIES ............... 11

II.1. Residues from sugar mills ............................................................................................. 12

II.2. Residues from palm oil mills ......................................................................................... 12

II.3. Residues from shea butter mills ..................................................................................... 13

II.4. Utilisation of the residues from oil mills ....................................................................... 13

Chapter II: PROBLEM STATEMENT,OBJECTIVES AND METHODOLOGY ...................... 14

I. PROBLEM STATEMENT .................................................................................................... 14

II. OBJECTIVES OF THE STUDY ......................................................................................... 14

III. METHODOLOGY .............................................................................................................. 15

III.1. Preliminaries ................................................................................................................. 15

III.1.1. Bibliographical research ....................................................................................... 15

III.1.2. Elaboration of questionnaire ................................................................................ 16



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III.2. Collection of data ......................................................................................................... 16

III.2.1. Preliminary visit to the mills ................................................................................. 16

III.2.2. Collection of data itself ......................................................................................... 16

III.3.Treatment of data and analyse ....................................................................................... 16

Chapter III: LITERATURE REVIEW .......................................................................................... 17

Chapter IV: MATERIALS AND METHODS .............................................................................. 20

I. EXPERIMENTAL SITE ....................................................................................................... 20

II. THE BY-PRODUCTS STUDIED ........................................................................................ 21

III. METHODS AND EQUIPMENTS ...................................................................................... 22

I.V. DIFFICULTIES FACED ................................................................................................... 23

Chapter V: ACHIEVEMENTS AND DISCUSSION ................................................................... 24

I. PRESENT SITUATION OF JUABEN OILS MILLS (JOM) ............................................... 24

I.1. Extraction of the by-products .......................................................................................... 24

I.1.1. By-products from palm tree ..................................................................................... 24

I.1.2. By-products from shea tree ...................................................................................... 26

I.2. Mill capacity and production of by-products .................................................................. 26

I.3. Fulfilment of the mills energy requirements ................................................................... 29

II. ENERGY DIAGNOSTIC ..................................................................................................... 32

II.1. Energy required in JOM ................................................................................................ 32

II.2. Energy normally available ............................................................................................. 34

II.3. Discussion ...................................................................................................................... 36

II.3.1. Energy currently available versus energy requirements ...................................... 36

II.3.2. Taking into account the energy derived from EFB and POME ............................. 39

Chapter VI: SUGGESTIONS ........................................................................................................ 40

I. FIBRE, SHELL, CAKE AND FILTERED CAKE ............................................................... 40

II. EMPTY FRUIT BUNCH (EFB) .......................................................................................... 41

III. PALM OIL MILL EFFLUENT (POME) ............................................................................ 43

CONCLUSION AND RECOMMENDATIONS .......................................................................... 46

REFERENCES .............................................................................................................................. 48

APPENDICES ............................................................................................................................... 50

ABSTRACT .................................................................................................................................. 66

RESUME ....................................................................................................................................... 67



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LIST OF FIGURES

Figure 1 : Diagram of cogeneration ................................................................................................ 6

Figure 2: Electricity and hot water co-production .......................................................................... 7

Figure 3: Heat recovery from engine .............................................................................................. 7

Figure 4: Combustion turbine ......................................................................................................... 8

Figure 5: Steam turbine ................................................................................................................... 8

Figure 6: The Combined cycle ........................................................................................................ 9

Figure 7: Different steps of the study ............................................................................................ 15

Figure 8: Design of the different sections of JOM ........................................................................ 20

Figure 9: Panorama of JOM fittings .............................................................................................. 20

Figure 10: Spaces where samples are drawn ................................................................................. 21

Figure 11: Full Fruit Bunch (FFB) ................................................................................................ 24

Figure 12: Section and structure of a palm fruit ............................................................................ 25

Figure 13: Palm oil by-products .................................................................................................... 25

Figure 14: Fresh shea fruit and shea seed drying .......................................................................... 26

Figure 15: Shea butter by-products ............................................................................................... 26

Figure 16 : Cogeneration in Juaben Oils Mills ............................................................................. 30

Figure 17 : Section of the prefurnace and the drum ...................................................................... 31

Figure 18: Seasonal energy requirement ....................................................................................... 33

Figure 19: Diagram of current potential versus energy requirements ........................................... 37

Figure 20: Treatment of EFB for energy recovery ........................................................................ 41

Figure 21: Treatment of POME for energy recovery .................................................................... 43



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LIST OF TABLES

Table 1: Conventional system versus cogeneration plant ............................................................. 10

Table 2: Summary of the methods used for solids by-products tests ............................................ 22

Table 3: Summary of the methods used for the tests on POME ................................................... 23

Table 4: Operating hours of work per season in JOM .................................................................. 27

Table 5: JOM average capacities for each season ......................................................................... 27

Table 6: Production of by-products per season ............................................................................. 28

Table 7: Annual production of by product in Juaben Oils Mills ................................................... 28

Table 8: Electrical power and steam required to process one ton of raw material ...................... 32

Table 9: Seasonal requirements in steam, power and total energy for each section ..................... 33

Table 10: Annual requirements of energy for the whole CPO, PKO and SB sections ................. 34

Table 11: GCV, moisture content and LHV of solid fuels ............................................................ 34

Table 12 Parameters of POME ...................................................................................................... 34

Table 13: Total energy potential of Juaben Oils Mills (JOM) ...................................................... 35

Table 14: Energy available in JOM without POME and EFB ...................................................... 36

Table 15: Electricity production with the excess of energy .......................................................... 38

Table 16: Electricity production with energy from EFB and POME ............................................ 39

Table 17: Electricity production with EFB ................................................................................... 42

Table 18: Electricity production with POME ............................................................................... 44



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INTRODUCTION

Energy is the driving force of human life; without energy no activity is possible and no

development can be envisaged. Gross Domestic Product (GDP) and energy consumption are

closely linked, the more a country consumes energy, the more developed it is. That is why after

the energy crisis of 1973, the International Community undertook to find a sure response to the

energy question. Before this crisis, the energy requirements were mainly met with fossil fuels.

However, these fossil fuels are great sources of pollutions and the worldwide reserves are

depleting. Therefore nowadays, people incline in favour of renewable energy sources such as

solar energy, wind energy, geothermal energy and especially biomass. Biomass gains much

interest because of the large possibilities it offers: production of biofuels, biogas, electricity, etc.

Biomass serves people in a “way that is efficient, clean, convenient and reliable and at the same

time is economically and environmentally sound” (FAO, 1995).

Furthermore, among the technologies which can be used to confer to biomass its so great

importance, we can list Cogeneration.

A Cogeneration plant allows using any type of fuel in general and biomass such as waste from

food processing industry in particular. Using by-products, electricity and heat are generated to

meet the energy requirements of the factory, making it energy self-sufficient.

It is against this background that the current study fits; the aim was to investigate the optimal

way to co-generate electricity and heat while using the by-products from an oil mills. Juaben

Oils Mills, a Palm Oil and Shea Oil industry in Kumasi (GHANA) has been chosen for that.

The work first of all specifies the backgrounds as well as the problem statement, the objectives

and the methodology of the study. Chapter 3 deals with a bibliographic synthesis. The

description of the methods, of the experimental mechanisms and of the measurements’ protocol

is tackled in the fourth chapter. The results and analysis constitute the fifth chapter of the report.

Some optimal methods to save energy are proposed in chapter six. Conclusion and

recommendation then follow.



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Chapter I: BACKGROUND This first chapter gives some information about the concept of cogeneration and the

availability of biomass as source of energy.

I. PANORAMIC VIEW ON COGENERATION

I.1. Definition

Cogeneration also calls Combined Heat and Power (CHP), is a technique to produce

simultaneously electric and thermal energies while using a same primary energy through a single

device. The corresponding efficiencies generally range between 80% and 90% (See Figure 1).

Figure 1 : Diagram of cogeneration

(Adapted from. “Technologies Propres et Sobres”)

In this technology, electricity is obtained from the conversion of the mechanical energy of a

turbine or an engine by an alternator. As for the heat, since it is less well transported like

electricity, it is often considered as an industrial waste. With cogeneration this option is avoided:

heat is recovered through a heat exchanger and used to produce either hot air or hot water or

again steam. In fact, an engine possesses an electric efficiency of 40 to 45 %, a turbine an

electric efficiency of 35 to 40 %, and those of fuel cells from 20 to 30%. Almost all the

difference of energy consumed is transformed into heat. Cogeneration consists on recovering at

the best this energy in order to increase the overall efficiency (electric plus thermal) and reach at

least 80 % (Wikipedia.org).

Figure 2 is an illustration of the co-production of electricity and hot water.



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Figure 2: Electricity and hot water co-production

(Adapted from fnf.org)

I.2. Types of cogeneration

Dealing with the type of cogeneration, the encyclopaedia “Wikipedia” highlights that this

depends on the devices installed as it is described below:

I.2.1. Cogeneration with engines

For small plants and for domestic applications people use cogeneration’s engines (electric

efficiency ranging between 30 and 40%). Here two types of thermal energies are produced, a low

temperature energy (about 95 °C), recovered from oil and water for cooling and a high

temperature energy (about 450 °C), recovered from exhaust gases. Figure 3 gives details on how

electricity and heat are produced from an engine

Figure 3: Heat recovery from engine (Adapted from petitecogeneration.org)

I.2.2. Cogeneration with gas turbines

Cogeneration can also be done while using a combustion turbine (a gas turbine). The

thermodynamic process of combustion turbines (electric efficiency varying between 25 and

40%) is characterized by Brayton’s cycle Atmospheric air is inhaled and compressed in a



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compressor. In the combustion chamber, a fuel is injected in this compressed air and is burned.

Hot and high pressure combustion gases are sent to a turbine which produces a mechanical work.

This work is transformed into electricity through an alternator. Since exhaust gases contain lot of

heat, they are aimed towards a boiler of recuperation, where their thermal energy will be

transmitted to a coolant fluid (water generally). See Figure 4.

Figure 4: Combustion turbine (Adapted from wikipedia.org)

I.2.3. Cogeneration with steam turbines

Apart from the technology described above, there is also the technology of steam turbine.

Figure 5 shows the functioning principle.

Figure 5: Steam turbine

(Adapted from wikipedia.org) Steam turbines are installed in industries capable to supply large quantity of steam. Rankine’s

Cycle governs the thermodynamic cycle of steam turbines. With heat released from the

combustion of, steam is produced at high pressure in a boiler. Then this steam is channelled

towards a turbine, where while relaxing, it drives the turbine. At the outlet of the turbine, steam

is condensed and is brought back to the boiler where the cycle restarts. Using this steam allows

increasing considerably the electric efficiency and to reach about 55%.



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I.2.4. Cogeneration with the combined cycle

The fourth way to implement cogeneration is the combined cycle. Indeed, it is possible to

combine steam turbine and gas turbine. As we said previously, gas turbine can produce steam

throughout a boiler of recuperation. This steam can drive a steam turbine instead of be used

directly for a process. And with an alternator set on the steam turbine axis; we can produce a

complement of electricity. This kind of configuration allows getting a high electrical efficiency

but a low thermal efficiency (See Figure 6).

Figure 6: The Combined cycle (Adapted from wikipedia.org)

I.2.5. Cogeneration with fuel cells

Cogeneration by fuel cells is in addition to the list above. This technology could be used in

domestic applications (heating and electricity production for individual houses) and industrials

ones. Unfortunately fuel cells are not yet a mature technology

I.3. Impacts of Cogeneration

Cogeneration also implies Energy, Economy and Ecology and is more than ever one of the

best answers to the energy requirements of the industrialists and the local authorities

(petitecogeneration.org).

I.3.1. Energy impact

Thanks to cogeneration, the potential of a fuel is efficaciously exploited; that is to say less

fuel is required to produce the same quantities of heat and electricity as a classical system,

separated production of only power or only thermal energy.

“Technologies Propres et Sobres” of January 1996 had published a comparison between a

cogeneration plant which has an overall efficiency of 87 % and a classical system, See Table 1.



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Table 1: Conventional system versus cogeneration plant

Data Conventional system

Cogeneration

Fuel (ue) 153 100

Electricity input (ue) 92 32

Electric efficiency (%) 37 32

Electric output (ue) 30 30

Electricity loss (ue) 62 2

Heat input (ue) 61 68

Thermal efficiency (%) 90 55

Thermal output 55 55

Heat loss (ue) 6 13

Overall output (ue) 85 85

Overall loss (ue) 68 15

(Adapted from. “Technologies Propres et Sobres”)

The conventional system is constituted of a power station having an electric efficiency of 37 %

and a boiler which has a thermal efficiency of 90 %. The comparison is based on the number of

unit of energy (ue) used to produce a same given quantity of energy (electricity and/or heat) by

each system. The loss due to each system is also taken into account. In the table ue means unit of

energy for instance the kWh

The gain of primary energy is: 35100)153

1001( =×− %.

That is why in the encyclopaedia “Wikipedia” Combined Heat and Power is designated as one of

the most energetically efficient techniques for the utilization of both fossil fuels and renewable

energies.

I.3.2. Economical impact

One of the economical impacts of cogeneration is the significant reduction of the energy bill,

that is to say the diminution of electricity bought to the grid and the optimization of thermal

energy’s cost. Another economical aspect is the benefit people can get from the resale of the

excess of electricity produced to the grid (petitecogeneration.org).

By 1996, the MW price was around 320 FHT in France. Some researchers had shown that with

cogeneration, it should pass to 166 FHT, that is to say a reduction of 48 %. Besides, according to

the types of fittings the payback period of Cogeneration plant is quite short and ranges between 3

and 5 years (Technologies Propres et Sobres).



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I.3.3. Environmental impact

Cogeneration also rhymes with the sustainable development and the rational utilization of

natural resources. It permits to reduce largely the emission of pollutants and greenhouse gases;

and this especially when we use renewable energy. Indeed, some researches estimate the

reduction of carbon dioxide (CO2) between 15 and 29 % according to the classical system

substituted by cogeneration (petitecogeneration.org). While producing 1000 MW by

cogeneration, the emission of CO2 is reduced for about 1.25 millions of metric tonnes per year

(Technologies Propres et Sobres). In addition, cogeneration helps to save fossil fuels owing to its

efficient (up to 80%) and to the possibility it offers to use renewable energy.

I.3.4. Impact on electricity distribution grid

Cogeneration is also a way for diversifying the techniques of energy production and for

developing local generation of electricity. In fact, contrary to the classical power stations which

are centralized, cogeneration plants are decentralized and close to the users i.e. urban centres,

industrial zones, hospitals, etc…Therefore all the loss by Joule effect due to electricity

transportation is avoided and the needs to reinforce the grid are dwindled. Furthermore, it assures

the reliability of electricity supply while preserving the zones supplied from blackouts…

I.4. Practice of cogeneration throughout the world

In USA, as early as 1980, cogeneration fittings were spread and their total capacity was

estimated in 1988 at 660 000 MW electric.

Cogeneration took its flight in Japan around 1985 with a total capacity of about 160 000 MW by

1992, the part of industrial cogeneration being 16 000 MW (Technologies Propres et Sobres).

Twelfth percent (12%) of the electricity in Europe is produced by CHP (petitecogeneration.org).

The three quarters (3/4) of this production are realized by Germany, Holland and Italy

(Technologies Propres et Sobres). In Denmark by 2000, the production of electricity by

cogeneration was more than 50 % of the country requirements (Wikipedia.org).

After this overview on the types of Combined Heat and Power (CHP), let us tackle the aspect of

the fuels.

II. AVAILABILITY OF BIOMASS FROM FOOD PROCESSING IN DUSTRIES

The followings lines show how, in many industries by-products are available as fuel and can

act as energy feedstock. Sugar industries, shea butter mills, and especially palm oil mills are the

food processing industries where enormous quantities of wastes are extracted and can be turned

into energy.



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II.1. Residues from sugar mills

Residues from sugar mills (i.e. bagasse) can provide more energy than what is required for

the process (FAO, 1995).

II.2. Residues from palm oil mills

Basiron and Chan (2004) found that the oil palm biomass is 7 times more available than

natural timber. “The palm oil industry is one of the food industrial sectors which produce the

highest quantities of residues” (FAO, 1995). Only 30 % of Fresh Fruit Bunch (FFB) is

transformed into oil, the 70 % remaining are waste; the waste is made up of Empty Fruit Bunch

(EFB), fibre, shell and Palm Oil Mill Effluent (POME). We will give more details on the way

these residues are extracted in the fifth chapter of this study. This availability of oil palm

biomass confers to it a place of choice.

Oil palm (Elaeis guineensis) initially found in the wild groves are nowadays grown like

plantation crops. One hectare of mature palms implies the availability of 20.08 FFB, of 4.42

EFB, of 2.71 fibres, of 1.1 shells, and of 13.45 POME in terms of fresh weight in Mt/year

(Sumiani, 2004).

In 25 years the world area of oil palm fields has increased by 6.81 millions hectares. From 1.76

millions hectares in 1980, we had in 2005 8.54 millions hectares. This situation is due to the high

demand of palm oil of oils refineries and soap industries throughout the world.

The figures got by Yong et al. for the year 2007 are yet more appealing, 184.6 millions Mt of oil

palm biomass has been produced in the world. With this production of residues, oil palm tree

become the top of fruit crops.

Tropical regions are the zones favourable to the cultivation of palm tree. That is why Asia and

Africa are the continents where we can find vast fields of palm tree. In Asia, 136.39 millions Mt

of palm oil are produced over 7.1 millions hectares harvested and 15.97 millions Mt of palm oil

are processed over 4.34 millions hectares for Africa (FAO, 2007).

Malaysia and Indonesia are currently the first and second best world producers of palm oil. The

process of 25 millions tons of CPO in these countries provides 30 to 50 millions Mt of by-

products at the mills (Dam, 2004).The Malaysian example in particular shows that if the annual

quantity of oil palm by-products generated in 2000 was 73.74 millions Mt, there were only 5.05

millions Mt of municipal solid waste, 2.177 millions Mt of sawdust, 1.327 millions Mt of paddy

wastes and 0.356 millions Mt of bagasse (Pusat Tenaga Malaysia, 2006).

Africa is the cradle of oil palm; and since nineteenth century (in the context of Industrial

Revolution in Europe) to 1966, was the largest producer and exporter of Crude Palm Oil (CPO)

and palm kernel. In 1911 for instance, 87,000 Mt of CPO and 157,000 Mt of kernels were



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exported from West African Anglophones countries like Nigeria, Ghana, Liberia, and Sierra

Leone, with 75 % from Nigeria. It is by 1966 that Malaysia and Indonesia had become the top of

the list in front of Nigeria and Zaire, the two first world producers of palm oil (FAO 148).

Besides, palm can be successfully cultivated in any African country where the rainfall is around

1600 mm/year such as Cameroon, Cote d’Ivoire, Ghana, Liberia, Nigeria, Sierra Leone, Togo,

Angola and Congo. This means that African can improve their level of production generate

impressive quantity of oil palm biomass.

One of the emerging food industries sector nowadays is the one of shea butter.

II.3. Residues from shea butter mills

Like for palm oil, the demand for shea fat is more and more increasing in the world. This

reality is due to high utilization of shear butter in cosmetics and as cocoa butter substitute in the

process of chocolate. Shea butter is extracted from the dried seeds of shea tree (Vitellaria

paradoxa) (journals.cambridge.org). The production of this butter gives at least 52 % of residues

called shea cake (practicalaction.org) which can also be used as fuel. Vitellaria paradoxa is

strongly widespread in Africa (Benin, Burkina Faso, Cameroon, Central African Republic, Chad,

Ethiopia, Ghana, Guinea, Guinea Bissau, Côte d’Ivoire, Mali, Niger, Nigeria, Senegal, Sierra

Leone, Sudan, Togo, Uganda, Zaire), (Wikipedia.org) and its waste therefore constitute an

important feedstock for energy. During more than 200 years, a shea tree provides between 15

and 20 kg of fresh fruit or between 3 and 4 kg of dried seeds per year.

II.4. Utilisation of the residues from oil mills

Even if the residues from food processing industries are available, they are not always use

for energy purpose. For instance, Empty Fruit Bunch (EFB) and Palm Oil Mill Effluent (POME),

which represent more than 70% of the biomass generated in a palm oil mills are very often used

either as fertilizer or disposed of, (Dam, 2004). EFB are mainly utilized for mulch. As for

POME, it is discharged in the nature (bushes and waterways), constituting thus a danger for the

environment (FAO 148).

In Africa, by-products from food industries are wasted. For instance, shells are mainly used as

fuel by the blacksmiths or help for the maintenance of the roads of palm plantations (FAO 148).



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Chapter II : PROBLEM STATEMENT,OBJECTIVES AND METHODOLOGY

The problem statement, the objectives and methodology of the study are specified in this

chapter.

I. PROBLEM STATEMENT

The aforementioned lines (like many others illustrations in literature) not only underlined

that biomass are largely available but raised the question of their valorisation and their optimal

utilization in the mills. Although some efforts have been done to use certain by-products (fibre,

shell, bagasse…) to meet the energy demand of the mills, the sector still continues to suffer from

wasting and inefficient utilization of the residues extracted.

The rapid growth of the number of oil palm plantations and the increasing attention paid to shea

butter, bring up concerns about the destination of the impressive quantity of residues which will

be extracted. The huge amount of waste from food processing industries can come up against our

endeavour to assure sustainable development if nothing is done to manage them efficiently.

How can we successfully convert all this abundant biomass into energy? Is there no scope for

cogeneration? Is cogeneration not a “windfall” for the conversion of waste from food industries

into energy? Is cogeneration not the best answer mainly for African food industries?

Most particularly how can cogeneration help to valorise and optimize the residues extracted in

Juaben Oils Mills for energy purpose?

This study wants to be a quite response to that latter question.

II. OBJECTIVES OF THE STUDY

Through this study, we aim to find out the best ways for energy savings in Juaben Oils Mills

(JOM). Determine how with cogeneration we can assure an optimal utilization of the industrial

waste of JOM for energy production constitutes our main objective.

The corresponding specifics objectives are:

Do an overall energy flow balance that is to say thermal and electric flow balances of

the cogeneration fitting.

Determine very clearly the utilization rate of by-products currently used as fuels and

identify those which are not yet used for energy production.

Suggest how to optimize the utilization of by-products. Here we would like to see if the

excess of fuels (if it is so) can be converted into electricity that will be sold to the Electricity

Company of Ghana (ECG) for Kumasi supply. In fact, Kumasi is a town where blackouts are

strident.



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III. METHODOLOGY

To reach the objectives of the study, the following methodology has been defined. Figure 7

sums up the different stages carried out.

Figure 7: Different steps of the study

III.1. Preliminaries

This stage has consisted in doing a bibliographical research that helped us to know on what

items we should focus on for our study and elaborate a befitting questionnaire.

III.1.1. Bibliographical research

Here it has been question on the one hand to familiarize ourselves with the concept of

cogeneration and to know what fuels (especially biomass) can be used in a Combined Heat

Power (CHP) plant. On the other hand this step helped us to master most of the technologies for

processing by-products from palm oil mill before their utilization as fuels.

Some papers and websites found through internet have been our sources



16

III.1.2. Elaboration of questionnaire

At this step we have formulated some questions to the technical staff of the mills especially

the Technical Manager and some technicians in charge of the Crude Palm Oil (CPO) section, of

the Palm Kernel Oil (PKO) section, of the Shea Butter (SB) section and of the cogeneration unit.

With whom we dealt with:

The characterization of by-products: identification, quantity extracted, current usages,

utilization rate and constraints

The check up of the cogeneration fitting : types and characteristics of the boilers and the

turbines

The guide of questionnaire is available in Appendix 1.

III.2. Collection of data

We want to clarify that our study was about the activities of Juaben Oils Mills (JOM) for the

period of June 2007 to May 2008.

III.2.1. Preliminary visit to the mills

This visit has allowed us to familiarize ourselves with the area of the study (different

sections of the mills) and to meet the technical personnel in order to organize the collection of

data.

III.2.2. Collection of data itself

This step has been punctuated with the followings actions:

Observe and understand succinctly the functioning of Crude Palm Oil (CPO), Palm

Kernel Oil (PKO) and Shea Butter (SB) sections but deeply the one of cogeneration.

Observe for a given period the amount of fuel currently consumed; the corresponding

consumption of water, the variations of the pressure of the steam generated and the variations of

the electric parameters.

Take samples of solid by-products for moisture content and calorific value experiments.

Measure temperature of Palm Oil Mill Effluent (POME) and bring some samples for

others tests in laboratory.

III.3.Treatment of data and analyse

Using the data collected we determined first of all the mill capacity befitting to the period of

the study, then from the total quantity of by-products extracted we deducted the surplus we can

save if some optimal measures are applied. We also emphasize on how to realize concretely

these measures



17

Chapter III : LITERATURE REVIEW What can we learn from the literature aptness to cogeneration and to the utilization of the by

products from food processing industries for energy purpose?

An overview on some biomass from food industries (in particular palm oil mills) which can be

valorised by cogeneration is given in this chapter.

One article of the Asian programme report (Wood Energy News) lists sugar mills and

palm oil mills as good sectors to implement cogeneration.

Sugar mills are energetically self-sufficient (even if their equipments are not efficient), thanks to

the utilization of bagasse. One metric ton (Mt) of sugarcane supplies 290 kg of bagasse

(equivalent to100 kWh) whereas the process required only 25 to 30 kWh/Mt and 0.4 Mt of

steam. Improve the fittings of sugar mills will permit to obtain more excess of bagasse and sell

the surplus of power generated to the grid. For instance, the annual electric potential of the

Association of South East Asian Nations (ASEAN) from bagasse was estimated in1995at 8600

GWh with an excess of 6800 GWh.

Things are quite the same with palm oil mills. In fact, 230 kg of Empty Fruit Bunch (EFB)

(equivalent to 35 kWh), 210 kg of fibre plus shell (equivalent to 45 kWh) and 6.5 m3 of biogas

are extracted from one metric ton (Mt) of Full Fruit Bunch (FFB). The energy required for the

process of one Mt of FFB is about 20 to 25 kWh and 0.73 Mt of steam. The utilization of only

fibre is capable to meet the energy requirements of a palm oil mill, highlight the authors.

Therefore the excess of by-products shell, EFB and Palm Oil Mill Effluent (POME) can be used

to produce a surplus of electricity that will be sold to the grid.

Mahlia et al. (2000) have conducted a study on the utilization of fibre and shell

(previously considered like industrial waste) as source of alternative energy for palm oil industry

in Malaysia and Indonesia. They proved that processing 30 metric tons (Mt) of Full Fruit Bunch

(FFB) per hour provides 4200 kg/h of fibre and 1800 kg/h of shell. In terms of energy this is

worth some 72, 083, 200 kJ/kg and is equivalent to 18,925 kg/h of steam. This is more than the

18,000 kg/h of steam necessary to generate the 600 kW of electricity required for the process.

The remaining of steam will be used to sterilize FFB.

How much the by-products from palm oil mills are available for alternative use? J.V.

Dam (2004) answers to this question through his research.

In Malaysia, 90 % of the fibres and the shells extracted are used as fuel by millers to meet their

energy demand. Contrary to fibre and shell, the utilisation rate of Palm Oil Mill Effluent



18

(POME) and Empty Fruit Bunch (EFB) ranges between 35 and 65 %. For palm oil millers, EFB

are less attractive as fuel for boiler and are therefore generally not used for energy but as

fertilizer. Similarly POME is also hardly used and creates a problem of accumulation in the

mills. Nevertheless, the author shows that generate electricity from EFB is 3.5 times more

profitable than use EFB as mulch in the plantations of oil palm.

Tau et al. (2007) through their research titled “Potential of hydrogen from oil palm

biomass as source of renewable energy worldwide” propose the best way for the valorisation of

palm oil waste. It is about the conversion of oil palm by-products (trunk, frond, EFB, shell and

fibre) into hydrogen thanks to the gasification in supercritical water (727 °C and 32 MPa). Using

the 184.6 millions metric tons (Mt) of oil palm waste available annually some 2.16 x 1010

kg/year of H2 (equivalent to 2.59 x 1015 GJ/year) will be generated. According to the authors, this

amount represents 50 % of the world hydrogen demand. The good news is that hydrogen can be

used as combustible in a cogeneration plant.

B.G Yeoh (2004) in one of his studies deals with the utilization of Palm Oil Mill

Effluent (POME) to generate heat and power. In Malaysia the best world producer of palm oil,

POME has been identified as one of the major sources of aquatic and atmospheric pollution. In

fact, 85% of the mills use lagoon systems to treat the 27 x 106 m3 of POME generated per year.

Therefore about 375 x.106 m3 of methane (CH4) are evolved. This amount represents 10% of

methane inventoried in Malaysia .In terms of greenhouse gas, this is worth 5.157 x 106 kg of

CO2. The author also reported that 30% of the Biochemical Oxygen Demand (BOD) load of

Malaysian waters is due to POME.

Fortunately, the biomethanation (anaerobic digestion) of POME under thermophilic condition

generates methane at a very high output, especially at 55°C; and then methane can be burned to

produce either thermal or electric energy.

In the whole, the palm oil in Malaysia contributes to 2,250 x 106 KWh annually (equivalent to

4% of the country electricity demand) and to 715 x 106 L of thermal energy.

Partial summary

Cogeneration is a way to valorise any type of fuels and especially residues from food industries.

In Africa there is enormous quantity of by-products from food industries which are considered as

waste and therefore thrown away. This happens may be because people ignore the technology of

cogeneration or because of economical reasons and absence of political incentives.



19

However, it is more than ever necessary for African countries to turn resolutely towards

renewable energy and mainly biomass as source of energy. Recently the price of goods in many

sub-Saharan countries has widely increased due to the rise of petrol cost.

Like in Asia may be cogeneration in food industries can increase Africa electric potential.

Nevertheless, studies dealing with the valorisation and optimization of the by-products from

African food industries thanks to cogeneration are scarce.



20

Chapter IV : MATERIALS AND METHODS In food industry, residues can be available but it is very important to investigate on their

characteristics in order to know if they can easily be used as fuels or if they require specific

treatments before their utilisation. It is the aim of this part which shows how during about 6

weeks (from 16th of April to 26th of May) we manage to collect our data. I. EXPERIMENTAL SITE

Our work has entirely been conducted in the oils mills of Juaben. The Juaben Oil Mills is a

joint venture between the Juaben Traditional Council and the Juaben Oil Mills Company

Limited. Initially it was a state farm established in 1977 until the government decided to sell the

farms in 1994. The Juaben Traditional Council bought the land and expanded the farm.

This industry was mainly constituted of 3 sections in particular the Crude Palm Oil (CPO)

section, the Palm Kernel Oil (PKO) section and Shea Butter (SB) section to which a refinery has

been added recently. All these sections are supplied by the boiler house (See Figure 8 and Figure

9).

Figure 8: Design of the different sections of JOM

Figure 9: Panorama of JOM fittings

SB section

Boiler house

CPO and PKO

sections



21

Our study doesn’t include the refinery but takes into account the 3 others sections and the boiler

house represented on Figure 9.

The complete process of Crude Palm Oil (CPO) and Palm Kernel Oil (PKO) production is

perceptible through the Appendix 2. Appendix 3 gives details on Shea Butter extraction.

II. THE BY-PRODUCTS STUDIED

All the by-products, used for our tests have been taken on the site Juaben Oils Mills.

Samples of fibre are drawn directly from the silo that fills mechanically fibre coming from CPO

section into the fuel conveyer. Shell, cake and filtered cake are taken from the platform where

they are stored just before their utilization. Empty Fruit Bunch (EFB) and Palm Oil Mill Effluent

(POME) samples are drawn from the stripper and at the exit of settling pond respectively (See

Figure 10).

Figure 10: Spaces where samples are drawn

FFuueellss ppllaattffoorrmm FFiibbrree ssiilloo

SSttrriippppeerr SSeettttlliinngg ppoonndd



22

III. METHODS AND EQUIPMENTS

The tests done on solid by-products (EFB, shell, cake and filtered cake) are the ones of

Gross Calorific Value (GCV) and of moisture content. The techniques and apparatuses used are

summarized in the following Table 2.

Table 2: Summary of the methods used for solids by-products tests

Parameters Technique used Devices Brief description of the method

GCV Adiabatic

combustion Bomb calorimeter and thermometer

-Combustion of 0.7 g of a sample with oxygen - the rise of temperature is measured thanks to a thermometer every 60 seconds till constant value

Moisture content

Drying with oven at 105 °C

Electric oven Memmert and Desiccators

-weight the (sample + basin) -Dry it first at least for 5 hours -Cool it in the desiccators for 30 minutes and weight again - Do so till getting constant mass

Calorific value experiments have been conducted in the laboratory of Mechanical Engineering

Department (MED) at Kwame Nkrumah University of Science and Technology (KNUST),

moisture content tests in the laboratory of Juaben Oils Mills (JOM).

As for Palm Oil Mill Effluent (POME) which is the sole liquid by-products, we worked on

the physicochemical parameters such as temperature, potential of Hydrogen (pH), Biochemical

Oxygen Demand after 5 days (BOD5) and Chemical Oxygen Demand (COD). Table 3 gives

more details about the techniques and devices used for each parameter. A brief description of the

methods applied is also recorded in the same Table 4.

The chemical tests listed above have been done in the laboratory of Civil Engineering

Department (CED) at KNUST.



23

Table 3: Summary of the methods used for the tests on POME Parameters Technique used Devices Brief description of the

method

Temperature Electronic

thermometer

Plunge thermometer in POME for at least 2 minutes before reading

pH Numeric method pH-meter with

combined electrodes

-Check first the pH-meter accuracy with neutral solution -Plunge it in the sample -Wait to get constant value before reading

BOD5 Winkler method

Titration with sodium thiosulphate (Na2SO3) 0.025 N

Airing water pump and incubator

-Prepare first diluted water -Dilute the sample and spill it in 2 BOD bottle - Put on bottle in incubator at 20°C for 5 days - Add 1ml of Maganous sulphate (MnSO4) follow by 1ml of alkaline iodide, invert the bottle and leave it settle. -Add 1ml of sulphuric acid (H2SO4) -Titrate 200ml of sample to have starch colour

COD

Opened reflux method Titration with di-ammonium

iron II sulphate (Fe2(NH4)2SO4.6H2O 0.0951

N

Extraction heater

-dilute the sample with distilled water -Add 10 ml of K2Cr2O7, 20 ml of H2SO4 (slowly) and cool it -Then add 1ml of Ag2SO4 plus some drops of mercury sulphate -After 2 hours of heating add 45 ml of distilled water and 3 drops of ferric indicator -titrate sample to have brown colour.

I.V. DIFFICULTIES FACED

The frequent blackouts in KNUST have strongly affected our experiments.

One other difficulty faced was the low accuracy of the thermometer of the calorimeter we used

for the experiments of Gross Calorific Value. The thermometer was 0.1 instead of 0.01.



24

Chapter V: ACHIEVEMENTS AND DISCUSSION The previous chapters allow us to collect all the indispensable information for the study..

The data got have been treated and analysed in order to master the current energy practices of

Juaben Oils Mills (JOM). This chapter which is made of 2 parts deals step by step with the

present situation and the energy diagnostic of the mills.

I. PRESENT SITUATION OF JUABEN OILS MILLS (JOM)

I.1. Extraction of the by-products

Let us remind that JOM is constituted of 3 main sections namely Crude Palm Oil (CPO)

section, Palm Kernel Oil (PKO) section and Shea Butter (SB) section. A refinery has just been

added to the mills but is not covered in this study.

The Palm Kernel Oil (PKO) section produces two by-products: a cake which is sold to poultry

farmers as feed stuffs and some oily residues from which oil are recovered by traditional method.

These 2 by-products are not taken into account in this study.

From Crude Palm Oil (CPO) section, Empty Fruit Bunch (EFB), fibre, shell and Palm Oil Mill

Effluent (POME) are extracted while cake and filtered cake emanate from SB section.

The following lines described how these by-products are derived.

I.1.1. By-products from palm tree

The palm tree (Elaeis guineensis) bears its reddish fruits in bunches weighing 10 to 40 kg

each, (FAO 148). See Figure 11.

Figure 11: Full Fruit Bunch (FFB)



25

A section of a fruit shows an outer skin (exocarp), a soft pulp (mesocarp), a shell (endocarp) and

the seed (kernel), (See Figures 12).

Figure 12: Section and structure of a palm fruit

While processing CPO and PKO (got from the fibrous pulp and the kernel respectively) EFBs

are extracted during the stripping, fibre is obtained from the mesocarp during the depericarping,

shell is removed after cracking of the nuts and POME is derived during clarification operation.

Figure 13 shows all these by-products (For more details, see Appendix 2)

Figure 13: Palm oil by-products

EEFFBB FFIIBBRREE

SSHHEELLLL PPOOMMEE



26

I.1.2. By-products from shea tree

A shea tree (Vitellaria paradoxa) provides between 15 and 20 kg of fresh fruit. The dried

seeds from shea fruit are the raw material for the production of Shea Butter (SB). (See Figure 14)

Figure 14: Fresh shea fruit and shea seed drying

Cake and filtered cake are obtained from shea dried seeds during the pressing and the filtration

respectively (See Figure 15 and refer to Appendix 3 for further details).

Figure 15: Shea butter by-products

I.2. Mill capacity and production of by-products

A Mill capacity is defined as the number of metric ton (Mt) of raw materials processed per

hour (Mahlia, 2000). The availability of Full Fruit Bunches (FFB) depends on the season of the

year; 3 seasons have been identified at Juaben Oils Mills.

During the peak season which starts from April and ends in June, 7.739 Mt/h have been

recorded. The mid season lasts 5 months, from July to October plus the month of March and has

an hourly average of 4.145 Mt/h. November to February represents the lean season with an

average of 2.295 Mt/h. Taking into account downtimes, time for repairing and maintenance and

based on the observations done on the mills, 20 hours/days (h/d) and 30 days/month (d/m) of

effective work have been assumed for the peak season. The assumptions are 20 h/d and 25 d/m

FFIILLTTEERREEDD CCAAKKEE



27

for the mid season and 18 h/d and 20 d/m for the lean season. All these assumptions are recorded

in Table 4.

Table 4: Operating hours of work per season in JOM

Season h/d d/m Total hours

Peak season 20 30 1800

Mid season 20 25 2500

Lean season 18 20 1440

The annual capacity reaches some 20,111 Mt per year in terms of Full Fruit Bunch (FFB)

processed and some 27,601 Mt per year for the whole of the 3 sections. Details are given in the

Table 5, Appendix 4 gives further information.

Table 5: Average capacities for each season in JOM

Peak season Mid season Lean season Annual amount

CPO section (Mt/h)

6.344 2.846 1.095 -

PKO section (Mt/h)

0.257 0.161 0.062 -

SB section (Mt/h) 1.138 1.138 1.138 -

Total capacity (Mt/h)

7.740 4.146 2.295 -

Total hours 1,800 2,500 1,440 -

Capacity of CPO(Mt)

11,419 7,115 1,577 20,111

Overall capacity (Mt)

13,931 10,364 3,305 27,601

As far as the residues generated are concerned, if we assume in percentage of mass the

values got by Umilkason et al. (1997), that is to say 21% of Crude Palm Oil (CPO), 23 % of

Empty Fruit Bunch (EFB), 14.5 % fibre, 6.5 % of shell, 6.5 % of kernel per kg of Full Fruit

Bunch (FFB), we deduce 29.5 % for Palm Oil Mill Effluent (POME). In terms of volume this is

worth 0.525 m3 of POME per Mt of FFB, result got by Yeoh in 2004.

For the cake and filtered cake we have 55.8 % and 6.2 % respectively since the extraction rate in

SB section is around 38% and we assumed that filtered cake represents 10 % of the waste.

Based on these assumptions, the computations lead to the hourly production of by-products per

season. All the figures are recorded in Table 6.



28

Table 6: Production of by-products per season

Residues Peak season Mid season Lean season

EFB (Mt/h) 1.459 0.655 0.252

Fibre (Mt/h) 0.920 0.413 0.159

Shell (Mt/h) 0.412 0.185 0.071

POME (m3/h) 3.331 1.494 0.575

POME (Mt/h) 0.430 0.193 0.074

Cake (Mt/h) 0.635 0.635 0.635

Filtered cake (Mt/h) 0.071 0.071 0.071

From Table 6 and base on the number of operating hours per season, the annual production of

each product is deduced. Figures are recorded in .Table 7.

Table 7: Annual production of by product in Juaben Oils Mills

Residues Peak season Mid season Lean season Annual production (Mt)

EFB (Mt) 2626.4 1636.5 362.7 4625.5

Fibre (Mt) 1655.8 1031.7 228.6 2916.1

Shell (Mt) 742.2 462.5 102.5 1307.2

POME (m3) 5995.1 3735.4 827.8 10558.3

POME (Mt) 774.8 482.8 107.0 1364.5

Cake (Mt) 1143.3 1588.0 914.7 3646.0

Filtered cake (Mt) 127.0 176.4 101.6 405.1

Empty Fruit Bunches (EFB) constitute the largest amount of residues (4,626 Mt/year), followed

by the cake (3,646 Mt/year). Fibre, Palm Oil Mill Effluent (POME) and shell occupy the 3rd, 4th

and 5th position with respectively 2,916 Mt/year, 1,365 Mt/year and 1307 Mt/year. Filtered cake

gives the lowest amount of waste with 405 Mt/year.

In JOM not all by-products are used for energy purpose: Shell, cake, filtered cake and

mainly fibre are used as fuels while EFB are burned for ash; the POME is thrown away after

traditional recovery of oil. Furthermore, interviews with the technical staff has revealed that

during the peak season there is an excess of fuels from which a part is stored (shell and cake) and

used like complement for the mid season. For the lean period, there is not enough fuel to meet



29

the requirements. As a result, JOM is obliged to go either around the village or far from the mills

in order to buy some shells and fibres with traditional millers of palm oil

I.3. Fulfilment of the mills energy requirements

To meet the energy requirements of the mills, steam and electricity are generated while using

one boiler and one turbine. The boiler is a combination boiler made up of a water-wall pre-

furnace and a conventional three pass fire tube which can use solid, liquid and gaseous fuels. The

maximum steam generation capacity of the boiler is 10,000 kg/h at 215° C and at a pressure

ranging between 15 and 20 bars. Its efficiency is up to 80% depending on the moisture content of

the fuel. As for the turbine, it is a back pressure type capable of producing 424 kW of power with

a live steam (coming from the drum) varying from 15 to 20 bars and an exhaust steam between

2.2 and 3.2 bars. Non condensing or back pressure turbine is useful when both heat and

electricity are required in an industry (FAO 148).

What happens there is that, the pre-furnace acts as the combustion chamber where solid fuels

(fibre, shell, cake and filtered cake) are burned to produce hot gases. These hot gases are then

transferred into the fire tubes of the drum where they help to heat pre-heated water coming from

the Feed Water Tank (FWT) and to get hot water which is sent to the parallels water tubes of the

pre-furnace. Since the water tubes are in direct contact with the strong flame of combustion wet

steam at high pressure are obtained at the outlet of the pre-furnace. Lead back to the drum wet

steam are dried while getting in contact with the upper part of the fire tubes which acts as a

super-heater.

The dried steam sent to the turbine follows 2 lines: the power line constituted of a Gear box that

drops down the turbine speed from 11,000 revolutions per minute (rpm) to 1,500 rpm. The

turbine is coupled to a Generator (alternator) which produces electricity; the second line is the

one which passes by the distributor. This latter distributes the remaining steam not used by the

power line to the different sections of the mills. A by-pass is used to send steam directly to the

distributor when there is no need of electricity.

An Induced Draught Fan (IDF) sucks the flue gas which is first cleared from ash thanks to an

Ash Discharge Hopper (ADH) before it is released through the chimney.

The steam generated is used for some processes in the 3 sections of the mills and to produce

electrical power. The electricity produced is used for the various sections of the mills, for the

buildings of the main administration, the offices of technical staff, the laboratory and the lighting

of the mills’ surroundings. Figures 16 and 17 are a summary of this section.

Cogeneration and Energy Savings in a Food Processing Industry: Case of Juaben Oils Mills in Kumasi

30

Figure 16 : Cogeneration in Juaben Oils Mills

Drum

FWT

ADH

Turbine GB Generator SS

IDF

Distributor

Refinery

CPO Section

SB Section

PKO Section

Prefurnace Fuels+Air

Blow down

Pre-heated water

Chimney

Power for processes and other uses

-Sterilization -Digestion -Clarification -Storage Tanks

-Dryer -Cooker -Storage Tanks

-Cooker -Storage Tanks

Flue Gas

DN 80, PN 25

Hot water

DN 150, PN 40

DN 100, PN 16

DN 80, PN 16 DN 80, PN 16

2 DN 100, PN 16/ 2 DN 80, PN 16

DN 250, PN 10

: Wet steam

: Dried steam

ADH: Ash Discharge Hopper GB: Gear Box FWT : Feed Water Tank SS: Steam Separator IDF : Induced Draught Fan


31

Figure 17 : Section of the prefurnace and the drum

FWT

Pre heated water

Hot water

Fuel +Air

Air

Dried steam By pass

Wet steam

Superheater

Water tube

Fire tube


Thesis written by Félicien D. BADOU/ 37th Promotion 2iE - June 2008 32

II. ENERGY DIAGNOSTIC

We define energy diagnostic like a meticulous analysis which on the one hand allows

identifying all the practices which are not sparing of energy, and help to find out the ways and

means to save energy on the other hand.

II.1. Energy required in JOM

Let us start by specifying the basic hypotheses. Relying on the work done by Malia et al.

(2000), we assume that to process one metric ton (Mt) of Full Fruit Bunch (FFB) into Crude

Palm Oil (CPO), 20 kWh and 500 kg of steam are required. Our readings and researches didn’t

permit us to get the corresponding figures for Palm Kernel Oil (PKO) and for Shea Butter (SB).

Thus we do the assumption that the production of one Mt of PKO and one Mt of SB represents

15.5% and 72% respectively of the energy consumed in the case of CPO. The 15.5 % of the PKO

derived from the kernel content of a FFB (6.5%) and the number of steps for its process compare

to CPO (21%), see Appendix 2. For the SB, we just compared the number of stages for its

production 8 against 11 for the CPO; this is in addition overestimated if we rely on the number

and types of machines of both sections. And finally, about 24 kg of steam is required to generate

1 kW of power (ratio between the boiler capacity 10,000 kg/h and the turbine power conversion

rate 424 kW) under the working pressure of 15 to 20 bars.

Hence the amount of steam required in kg to process one Mt of:

FFB is 9805002420 =+×

PKO is 151.99800.155 =×

SB is 705.69800.72 =×

All these basic hypotheses are mentioned in the table below.

Table 8: Electrical power and steam required to process one ton of raw material

Parameters Electrical energy

(kWh/Mt)

Steam required

(kg/Mt)

Total steam required

(kg/h)

CPO 20 500 1140

PKO 3.1 77,5 151.9

SB 14.4 360 705.6

(Adapted from Mahlia et al. 2000)

Considering the mills capacity befitting to each season (Table6 and the Table 8), we can

calculate the thermal and electrical energies demands of the different sections of JOM. The

computations are summarised in Table 9.



Table 9: Seasonal requirements in steam, power and total energy for each section

Peak season Mid season Lean season

Power (kW) Steam (kg/h) Power (kW) Steam (kg/h) Power (kW) Steam (kg/h)

CPO 126.9 3,171,9 56.9 1,422,9 21.9 547.5

PKO 0.8 19.9 0.5 12.5 0.2 4.8

SB 16.4 409.8 16.4 409.8 16.4 409.8

Total 144.1 3,601,6 73.8 1,845,2 38.5 962.1

Total steam (kg/h) 7,059,2 3,616,5 1,885,7

Total energy (GJ/h) 18.3 9.4 4.9

The total energy (electrical and thermal) in Table 9 is computed with the following formula:

required steam total2,590J/h)required(kEnergy ×=

It is assumed that 2,590 kJ of energy is needed in order to generate 1 kg of steam (Mahlia, 2000).

Figure 18 shows the energy requirement per season.

02468

101214161820

En

erg

y re

qu

ired

(G

J/h

)


Season

Seasonal energy requirement

Figure 18: Seasonal energy requirement As a result, 18.3 GJ/h are necessary for the peak season while the mid and lean seasons required

9.4 GJ/h and 4.9 GJ/h respectively.

The following table gives information about the annual requirements of energy.



Table 10: Annual requirements of energy for the whole CPO, PKO and SB sections

Peak season Mid season Lean season Annual amount

Electricity (GWh) 0.259 0.185 0.055 0.499

Steam (Mt) 6483.126 4613.272 1385.428 12481.826

Total steam (Mt) 12706.927 9042.013 2715.439 24464.379

Total energy (GJ) 32910.942 23418.814 7032.986 63362.743

Around 0.5 GWh of electricity and 12,482 Mt of steam are required to meet the requirements of

3 sections of the mills per year. This is worth some 63,363 GJ for the overall energy demand.

II.2. Energy normally available

The experiments of Gross Calorific Value (GCV) done for each the solid by-product will

help us to know the energy we can obtain. Table 11 gives the average of the values got (all data

about the variation of temperature and moisture content are available on Appendix 5).

Table 11: GCV, moisture content and LHV of solid fuels

By-products GCV (kJ/kg) Moisture content (%) LHV (kJ/kg)

EFB 17,458 62 6,634

Fibre 18,625 32 12,665

Shell 19,194 17 15,931

cake 19,482 25 14,612

Filtered cake 25,794 4 25,794*

The energy from Palm Oil Mill Effluent (POME) is obtained thanks to its biomethanation

into biogas.

In Table 12, the data got for our sample (details are given on Appendix 6).are compared to those

found by Yeoh in 2004.

Table 12 Parameters of POME

Parameters POME Values got by Yeoh

Temperature (°C) 56.5 80-90

pH 4.94 4.7

BOD5 (mg/l) 4,594 25,000*

COD (mg/l) 47,1670 50,000



The parameters got for our samples are almost close to the ones found by Yeoh in 2004.

Therefore we can assume that 1 m3 of POME provides 12.4 m3 of methane and since methane

has a Net Heating Value of 1,011 Btu/ft3 (Engineering tool box.Com) or 37,710 kJ/m3, we do a

rule of three to find the yield 1 m3 of POME in term of energy:

467,6043771012.4 =× kJ/m3

With the heating values of each by-product, the overall quantity of energy available is calculated

while using the following formulas:

For each by-product: Quantity(ton/h)×LHV(kJ/kg)

Energy(GJ/h)=1000

For all of them : ( )Total_Energy(GJ/h)= Energy_i ×η∑

Where η is the efficiency of the boiler: 80% (we took the lowest value).

All the details of our computations are given in the Table 13.

Table 13: Total energy potential of Juaben Oils Mills (JOM)


EFB

Quantity (Mt/h) 1.459 0.655 0.252

LHV (kJ/kg) 6,634 6,634 6,634

Energy (GJ/h) 9.7 4.3 1.7

Fibre

Quantity (Mt/h) 0.920 0.413 0.159

LHV (kJ/kg) 12,665 12,665 12,665

Energy (GJ/h) 11.6 5.2 2.0

Shell

Quantity (Mt/h) 0.412 0.185 0.071

LHV (kJ/kg) 15,931 15,931 15,931

Energy (GJ/h) 6.6 2.9 1.1

Cake

Quantity (Mt/h) 0.635 0.635 0.635

LHV (kJ/kg) 14,612 14,612 14,612

Energy (GJ/h) 9.3 9.3 9.3

Filtered Cake

Quantity (Mt/h) 0.071 0.071 0.071

LHV (kJ/kg) 25,794 25,794 25,794

Energy (GJ/h) 1.8 1.8 1.8

POME

Volume (m3/h) 3.330 1.494 0.575

NHV (kJ/m3) 467,604 467,604 467,604

Energy (GJ/h) 1.56 0.70 0.27

TOTAL ENERGY (GJ/h) 32.4 19.5 12.9



This table clearly shows that the energy potential of JOM for the peak season is 32.4 GJ/h, 19.5

GJ/h and 12.9 GJ/h for both mid season and lean season.

The problem here is that not all this potential is currently available in JOM since Empty Fruit

Bunch (EFB) and Palm Oil Mill Effluent (POME) are not used for energy purpose. Owing to this

fact the amount of energy that should normally be available per season is given in Table 14:

Table 14: Energy available in JOM without POME and EFB


Fibre

Quantity (Mt/h) 0.920 0.413 0.159

LHV (kJ/kg) 12,665 12,665 12,665

Energy (GJ/h) 11.6 5.2 2.0

Shell

Quantity (Mt/h) 0.412 0.185 0.071

LHV (kJ/kg) 15,931 15,931 15,931

Energy (GJ/h) 6.6 2.9 1.1

Cake

Quantity (Mt/h) 0.635 0.635 0.635

LHV (kJ/kg) 14,612 14,612 14,612

Energy (GJ/h) 9.3 9.3 9.3

Filtered Cake

Quantity (Mt/h) 0.071 0.071 0.071

LHV (kJ/kg) 25,794 25,794 25,794

Energy (GJ/h) 1.8 1.8 1.8

TOTAL ENERGY (GJ/h) 23.5 15.4 11.4 Without EFB and POME the energy really available per hour drops around 28% for the peak

season, 21 % for mid season and 12 % for the lean season.

II.3. Discussion

Many questions can be raised in relation to the tables and diagrams above. Table 13 and

Table 14 about the availability of energy and Figure 19 about the seasonal energy requirement,

inspire us the followings reflections.

II.3.1. Energy currently available versus energy requirements

Here we compare the energy currently available (obtain from the utilization of fibre, shell,

cake and filtered cake) with the overall requirements of the Crude Palm Oil (CPO) section, the

Palm Kernel Oil (PKO) section and the Shea Butter (SB) section. Figure 19 illustrates this

comparison:



0.0

5.0

10.0

15.0

20.0

25.0

Ene

rgy

(GJ/

h)


Season

Current potential versus Requirements

Current potential Requirements

Figure 19: Diagram of current potential versus energy requirements

This diagram shows that whatever the season there is a surplus of energy. Indeed the excess of

energy decrease from the peak season to the lean season at the rate of 5.2 GJ/h, 6 GJ/h and 6.5

GJ/h. This variation of the surplus of energy can be explained by the fact that the production of

Shea Butter (SB) (so the availability of cake and filtered cake) is constant during the year while

the process of Crude Palm Oil (the most consumer of energy) is the least during the lean season.

In others terms, the energy requirements of the lean season is the lowest even though the energy

obtained from cake and filtered cake are constant during the year. This obvious since the rate of

CPO production on the one hand and the consumption of fibre and shell on the other hand are the

same for all the seasons.

Nevertheless, we don’t forget that while doing ours investigations, it has been revealed that

during the peak season there is an excess of fuel which is used to complete the energy of the mid

period; for the lean season JOM sometimes recourses to outside. According to ours computations

which are based on the current generation of residues in the mills, this situation should not

happen. If it is so, it means that there is some thing wrong namely a waste of fuels throughout the

year and especially during the peak season where by-products are abundant. For instance the

survey of fuel consumption during the peak season gave us a rate of 1.3 Mt/h (of which we

assume 50 % of fibre, 20 % of shell, 20 % of cake and 10 % of filtered cake). This 1.3 Mt/h of

fuel is worth some 19.5 GJ/h (See Appendix 7). Compared to the requirements of the peak

season (18.3 GJ/h) we deduce an excess of 1.2 GJ/h.



We humbly thing that it will be interesting to apply this African proverb: “When it is raining in

your home today, reserve some rains water that you will use when the drought will occur”.

There is one difficulty, we can on the other hand recognize. It is about the non continuous

availability of by-products during the lean season due to the drop in Crude Palm Oil (CPO)

production even though the boiler needs to be fed up continuously. But this difficulty can be

overcome either if we manage very well the excess of fuel of the peak season and use a part for

the lean season or if we use a part of the energy extracted from the Empty Fruit Bunch (EFB)

and the Palm Oil Mill Effluent (POME). This latter case is elucidated in the coming paragraph.

What is important to notice here is that throughout the whole year there is an excess of energy.

The table below gives the amount of electricity that can generated solely with the surplus of

energy got after meeting the total requirements of all the processes: some 3.75 GWh.

Table 15: Electricity production with the excess of energy

Seasons Total hours Hourly excess (GJ/h) Energy per season (GJ) Electricity (GWh)

Peak season 1800 5.2 9,360 1.04

Mid season 2500 6 15,000 1.67

Lean season 1440 6.5 9,360 1.04

Total electricity production (GWh/year) 3.75

The hourly excess has been calculated while timing the boiler efficiency (80%) by the difference

of energy between the requirements and the energy available. We took an efficiency of 40 % for

the turbine that is to say for the conversion into electricity.

In all the previous calculations, we did not take into account the electric consumptions for

other purpose i.e. buildings of the main administration, offices of the technical staff, the

laboratory and the lighting of the different sections, of the mills yard and its surroundings.

During the study, we needed the electrical consumption for other purpose in order to deduce the

real amount of electricity we can save only while improving the current practices in the mills;

but we did not find it. Therefore, if we assume that 60 % of the electrical production of the mills

is consumed for the others purposes (equivalent to 2.25 GWh per year), we save some 1.5 GWh

per year. In others terms, this means that just with an optimization of the current practice of the

mills 1.5 GWh of electricity can be saved per year.

Now let’s deal with the amount of electricity we can save if we include EFB and the POME.



II.3.2. Taking into account the energy derived from EFB and POME

As stated previously, in JOM Empty Fruit Bunch (EFB) and Palm Oil Mill Effluent (POME)

are not used for energy purpose. The following lines show how in the contrary it is beneficial to

use them to generate electricity.

From Table 13 where an overall energy balance of all the by-products has been done, we extract

the part of the EFB and the POME; this gives us: 8.9 GJ/h for the peak season, 4.1 GJ/h for the

mid season and 1.5 GJ/h for the lean season. The amount of electricity we can obtain is recorded

in Table 16.

Table 16: Electricity production with energy from EFB and POME

Periods Total hours Hourly energy (GJ/h) Energy per season (GJ) Electricity (GWh)

Peak season 1800 8.9 16,020 1.78

Mid season 2500 4.1 10,250 1.14

Lean season 1440 1.5 2,160 0.24


The utilization of EFB and POME for energy purpose by cogeneration will help to produce some

3.17 GWh of electricity per year. To find out the hourly energy, we time the initial energy value

of EFB plus POME befitting to each season by the boiler efficiency (80%). We assumed 40 % as

the efficiency of the turbine.

Nowadays, everywhere people claim sustainable development. We should not only reason at the

individual scale, we need to fit into our immediate environment. When we know that in Kumasi

high power demand leads to frequent blackout and that in Juaben Oils Mills at about 40

kilometres away there is a real potential for generating electricity thanks to cogeneration, we are

in hurry that this become a reality. In addition this will be economically profitable for the JOM

through the sale of the surplus of electricity generated to Electricity Company Ghana (ECG). It

will also be of social benefit to the population of Kumasi.



Chapter VI : SUGGESTIONS What is considered useless by one person is sometimes thought as useful by another person.

This can be applied to palm oil by-products. In palm oil industry “very little attempt is made to

save energy” (Dam, 2004) because of the large amount of by-products which even used

inefficiently help to meet the requirements of the mills. Fibres and shells are wasted while Empty

Fruit Bunch (EFB) and Palm Oil Mill Effluent (POME) are not used for energy purpose.

In this part we propose some ways for the optimization and valorisation of the by-products

studied.

I. FIBRE, SHELL, CAKE AND FILTERED CAKE

In order to reach rapidly the pressure required (between 15 and 20 bars) the furnace is often

overloaded either by the fibres transferred from the Crude Palm Oil (CPO) section or the shell,

cake and filtered cake filled in the conveyor. This happens because there is no specific

instruction on the utilization rate of the fuel that is to say a .precise quantity of fuels to use per

hour according to the activity of the mills. Base only on the variations of pressure (15 to 20 bars)

for loading the furnace can lead to enormous loss of fuels.

One other thing is that the quantity of air in Juaben Oil Mills (JOM) is less than the air of

combustion required. This latter is defined like the sum of the extra air added to the theoretical

air, minimum quantity of air for a complete combustion. If we consider the air fuel ratio got by

Malia et al. (2000) i.e. 8.039, this lead to a requirement of 4.6 kg/s of air for the peak season, 2.9

for the mid season and 2.1 for the lean season. In JOM the calculations of air flow have given 1.6

kg/s for the peak and mid seasons and 1.1 kg/s for the lean seasons (see Appendix 8). These

figures are almost 2 times less than the ones necessary.

The information aforementioned but also the presence of pure combustible in the refuses, the un-

burnt matters of the products of combustion and sometimes the black dark colour of flue gas,

show that there is incomplete combustion.

A good load of furnace based on the amount of fuel really needed per period while taking into

account the air fuel ratio can help to save fuels. Instructions based on the figures found in this

study can be given for the loading of the boiler.

Another solution is to automate the loading of the boiler so that according to the season and the

activities of the mills only the exact amount of fuels required will be sent automatically to the

furnace.

.



II. EMPTY FRUIT BUNCH (EFB)

The utilization of only fibre and shell can help a palm oil mill to be self-sufficient. The

treatment of EFB will therefore allow having a surplus of fuel that will be converted into

electricity by cogeneration. This is yet possible in JOM. In fact, the present utilization rate of the

boiler ( 7.30.82590(kJ)

23,5(GJ/h) =× Mt/h) is less than its maximum capacity 10 Mt/h

We assumed that all the amount of fibres, shells, cakes and filtered cakes extracted during the

peak season are consumed hour after hour.

The constraints that people base on for using EFB as fertilizer instead of energy feedstock are:

“the assumed low level of residual oil, the high water moisture content (around 65 %) and the

difficulty in handling due to its bulky and fibrous nature” (Jorgensen, 1985).

Today all these brakes have been overcome. In addition to the dewatering of EFB to make it

available for the boiler and the utilization of the resulting ash, further oil can be recovered.

The figure below shows concretely how this happens.

Figure 20: Treatment of EFB for energy recovery (Adapted from Jorgensen, 1985)



What is first of all very interesting in the treatment of EFB for energy purpose is that the slices of

dried pressed EFB (17,458 kJ/kg) burn approximate like fibre (18,625 kJ/kg) and shell (19,194

kJ/kg).

Besides, the ash resulting from its combustion is very rich. It is reported that it contains

(Potassium (K): 2.24 %, Nitrogen (N): 0.44 %, Magnesium (Mg): 0.36 %, Calcium (Ca): 0.36 %,

Phosphorus (P): 0.144%, of dry matter (Malaysian-Danish Environment Cooperation, 2006) and

can be used as a fertilizer at the same way like the raw EFB.

Instead of either throw away EFB or incinerate them in the open air which is a source of

pollution, it will be interesting to treat them and extract their potential energy before we use the

resulting ash as a fertilizer. Doing so, we gain 2 times.

If Juaben Oils Mills (JOM) starts using EFB as fuel 3 advantages will be derived:

Electricity production: the following table gives the amount of electricity we can have

from EFB.

Table 17: Electricity production with EFB


Peak season 1800 7.76 13,968 1.55

Mean season 2500 3.44 8,600 0.96

Lean season 1440 6.5 1, 958,4 0.22


2.73 GWh per year, here is what JOM can gain from the pre-treatment of EFB for energy

purpose: The hourly energy has been calculated while timing the boiler efficiency (80%) by the

crude hourly energy of EFB befitting to each season. We used an efficiency of 40 % for the

turbine.

Oil recovered : According to Jorgensen ,the rate is 0.35 % of the weight of FFB

Therefore, we will have as Oil recovered: 0.0035×20111=70.4 Mt.

In addition to the electricity generated some 70.4 Mt of oil recovered could be sold for further

benefit.

Ash for organic amendment

It is reported that 5 kg of ash are obtained from 230 kg of EFB which is the yield of one metric

ton of FFB. Thus we shall have 100,555201115 =× kg of ash per year to use as fertilizer in order

to increase the yield of palm plantation.



On an economical point of view, owing to a lack of time, we didn’t have the prices which prevail

on the Ghanaian market to do an economical analysis. Yet, Jorgensen in 1985 showed that the

total cost (investment cost to buy single screw press and bunch splitter inclusive installation cost

plus the operational cost) can be covered only in one year with the income from the sale of oil

recovered and from the money save for steam production with EFB instead of petrol.

III. PALM OIL MILL EFFLUENT (POME)

In the majority of the palm oil mills, the effluents got from the process of CPO are either

directly discharged or partially treated through lagoon system before their discharge in the

nature. Millers for economical reasons or by ignorance limit themselves to the system of pond

treatment in order to meet the environmental instructions in force (Yeoh, 2004). In either case,

this constitutes a great source of aquatic and atmospheric pollution (Yeoh, 2004) but also a

source of land deterioration (FAO 148). Fortunately thanks to biomethanation, POME can be

transformed into methane. Methane then can be used like the previous solid fuels to generate

steam and power. And the remaining liquid from POME can act as fertilizer. The extraction of

biogas has a high yield (65%) under thermophilic condition (Yeoh, 2004). This latter condition is

easily obtainable in our case since the average of temperature of POME is 56.5 °C.

There are 2 stages in biomethanation of POME: an anaerobic digestion in a closed-tank

bioreactor and the recovery of biogas. See Figure 21.

Figure 21: Treatment of POME for energy recovery (Adapted from Yeoh, 2004)



What we can suggest to JOM is to produce the maximum of methane during the peak season

(continue also during the others seasons) which will be stored. During the lean season the

methane stored will be used to generate steam (with the same boiler since its grate is adaptable

and can use a gaseous fuel) which will be transferred to the turbine for electricity production.

For that if we rely on the work done by Yeoh in 2004, we will need the following facilities:

Size of anaerobic reactor (we took figures of peak season, the most constraining):

time(d)Retention_FFB)_(m3/Mt _ratePOMEFFB/h)_(Mt_hour/day)(Operating(m3)Reactor ×××=

466.370.5256.34420Reactor =×××= m3

Storage vessels size:

∑××= )FFB/period_(MtE)(m3/m3_POM eBiogas_ratFFB)_(m3/Mt Pome_rate(m3) Vessel

68,628,820,1116.50.525 Vessel =××= m3

For JOM an anaerobic reactor of 500 m3 and storage vessels of 69,000 m3 will be necessary.

The production of electricity that we could obtain from POME is mentioned in Table 18.

Table 18: Electricity production with POME


Peak season 1,800 1.25 2,250 0.25

Mean season 2,500 0.56 1,400 0.16

Lean season 1,440 0.22 316,8 0.04


With the anaerobic digestion of POME for the extraction of methane instead of discharge it in

the nature some 0.44 GWh could be generated. The computations have been done exactly like

for the EFB.

Furthermore, the liquid from the anaerobic reaction, owing to its nutrient value can help to water

the farms during the dry season and enhance very significantly the yield of palm trees from 10%

to 23 % according to Yeoh (2004).

The 10,558.30.52520,111 =× m3 of POME treated could be used to water

31.5210,0000.067

10,558.3 =××

hectares of palm trees, assuming that the watering will occurs for 6



months per year since in Ghana there are 6 rainy months. We used an application rain equivalent

of 6.7 cm per year (Yeoh, 2004).

The time assigns to our work doesn’t allow us to do a cost benefit analysis based on current

prices of facilities in Ghana. However the study done by Yeoh in 2004 on the utilization of

POME under the temperature of 55°C for heat generation (in our case steam for the turbine) and

land application gives a pay back period of 1.5 year. This means that in less than 2 years the

money invested will be recovered and the period of maximum benefit will start.

Partial summary

From the section “Energetic Diagnostic” and the chapter “Suggestions”, it is noted that, that

only with an optimal utilization of the fibre, shell, cake and filtered cake some 1.5 GWh could be

saved. If furthermore EFB and POME are pre-treated, then used for energy purpose we could get

2.73 GWh and 0.44 GWh per year respectively. In addition to the fact that this electric

production could be sold to Electricity Company of Ghana (ECG), from EFB 100.6 Mt of ash

and 70.4 Mt of residual oil can be extracted while the digested liquor from POME can act as

fertilizer to enhance the yield of more 30 hectares of palm oil plantation.



CONCLUSION AND RECOMMENDATIONS

This study has reviewed deeply how with cogeneration, heat and power can be produced

from the waste of Juaben Oils Mills (JOM) namely fibres, shells, cakes, filtered cake, EFB and

POME. With the energy generated, it is first possible to meet very largely the energy

requirements of the mill (some 2.75 GWh and 24,464 Mt of steam per year) and then use the

excess to produce especially electricity that will be sold to Electricity Company of Ghana (ECG).

Indeed, an efficient utilization of the 8,274 metric ton of residues currently combusted per

year in the mill (fibre, shell, cake and filtered cake) that is to say the harmonization of the

amount of fuel required per hour with the quantity of air of combustion will insure the energy

self sufficiency of the mills and help to save some 1.5 GWh per year.

In addition with the 4,626 metric ton (Mt) of Empty Fruit Bunch (EFB) extracted from the

20,111 Mt of Full Fruit Bunch (FFB) processed per year some 2.73 GWh could be generated if

the mill consents to pre-treat them by splitting and dewatering. This option will also allow

having some 100.6 Mt of ash for land application and 70.4 Mt of residual oil recovery.

Besides, the Palm Oil Mill Effluent (POME) resulting from the production of Crude Palm Oil

(CPO), reach about 10,558.3 m3 annually and should help to produce 0.44 GWh per year thanks

to biomethanation followed by Combined Heat and Power (CHP) technique. One other benefit

from doing so is the production of nutritious digested liquor for the watering of more than 30

hectares of palm oil plantation of which the yield should be enhanced around 10 to 23 %.

On the whole thanks to cogeneration from its biomass Juaben Oils Mills can meet all its steam

and power requirements and get a surplus of 4.67 GWh per year.

The good news is that all this great possibility that offers palm oil and shea butter industries

to convert biomass into energy is feasible with others food processing industries such as sugar

mills, chocolate mills, rice mills and also with sawmills.

Since Africa abounds plenty fields where the raw materials used in these industries can be

harvested, time is not up for African food industrialists to integrate cogeneration with residues in

their business?

It is important to recognize that in our computations we did not get the exact energy

requirements of Palm Kernel Oil and Shea Butter sections as well as the annual electrical

consumption of the mill for others purposes. Further works are recommended in order to find out

these values and take them into account in the calculations.

It will also be very interesting to conduct a meticulous analysis to emphasize the cost of EFB and

POME treatments and the income that we can get. Further economical studies are deeply

recommended to emphasize how far it will be beneficial to use the excess of fuel to generate



electricity that will be sold to the grid while taking into account the requirements of the refinery

newly installed in JOM.

Thanks to cogeneration the price of electricity will likely decrease for the happiness of the

millers first but mainly for the one of the population since the price of some manufactured goods

will thus drop. To confirm or to invalidate this possibility researches and studies are necessary.



REFERENCES

Azali A., A.B. Nasrin, C., 2005. Development of gasification system fuelled with oil palm fibres and shells. American Journal of Applied Sciences (special Issue): 72-75. Basiron, Y., Chan, K.W., 2004. The oil palm and its sustainability. Journal of Oil Palm Research 16, 1–10. Dam J.V., November 2004. Palm oil production for oil and biomass: the solution for sustainable oil production and certifiably biomass production? Food and Agriculture Organization, FAO. Regional Wood Energy Development Programme in Asia, September 1995. Cogeneration in wood and Agro Industries. Food and Agriculture Organization, FAO. Small scale palm oil processing in Africa. Bulletin 148. Not dated Food and Agriculture Organization, FAO. Statistics Division, 2007. Goldemberg, J., 2006. The promise of clean energy. Energy Policy 34, 2185-2190. Jorgensen HK, February 1985.Treatment of empty fruit bunches for recovery of residual oil and additional steam production. JAOCS 1985; 62(2):282-4. Kelly-Yong T.L., K.T. Lee, M., et al, 2007. Potential of hydrogen from oil pal biomass as a source of renewable energy worldwide. Energy Policy 35, 5692-5701. Mahlia T.M.I., M.Z. Abdulmuin, A., et al, 2000. An alternative energy source from palm wastes industry for Malaysia and Indonesia. Energy Conversion and Management 42, 2109-2118. Malaysian-Danish Environment Cooperation Programme Renewable Energy and Energy Efficiency Component, January 2006.Barrier Analysis for the Supply Chain of Palm Oil Processing Biomass (Empty Fruit Bunch) as Renewable Fuel. Pusat Tenaga Malaysia, 2006. Biomass for electricity generation in Malaysia.

Available at: /http://www.ptm.org.myS. TECHNOLOGIES PROPRES ET SOBRES, N°2 January 1996. Les enjeux économiques de la cogénération. Umikalsom, M.S., Ariff, A.B., Zulkifli, H.S., Tong, C.C., Hassan, M.A., Karim, M.I.A., 1997. The treatment of oil palm empty fruit bunch fibre for subsequent use as substrate for cellulase production by Chaetomium globosum kunze. Bioresource Technology 62, 1–9. Yeoh B.G., January 2004. A technical and economical analysis of heat and power generation from biomethanation of palm oil mill effluent. Yusoff S., September 2003. Renewable energy from palm oil-innovation on effective utilization of waste. Journal of Cleaner Production 14, 87-93.



WEBSITES

http://fr.wikipedia.org/wiki/Cog%C%A9n%A9ration http://journals.cambridge.org/action/displayAbstract;jsessionid=607577C05AF253E904807A7E88E7EBDF.tomcat1?fromPage=online&aid=1704332 http://practicalaction.org/practicalanswers/product_info.php?products_id=265 http://www.engineeringtoolbox.com http://www.fnh.org/naturoscope/Energie/Cogeneration/Cogen1.htm http://www.petitecogeneration.org/index.php



APPENDICES

APPENDIX 1: Questionnaire to Juaben Oils Mills ……………………………………………..52

APPENDIX 2: Overview of Crude Palm Oil (CPO) and Palm kernel Oil (PKO) sections …….56

APPENDIX 3: Overview of Shea Butter section ……………………………………………….57

APPENDIX 4: Daily overview of CPO, PKO and SB and the Mill Capacity ………………….58

APPENDIX 5: High Calorific Value (HCV) and moisture content……………………………..61

APPENDIX 6: Parameters of Palm Oil Mill Effluent (POME) ………………………………...64

APPENDIX 7: Consumption of fuel during the peak season…………………………………...65

APPENDIX 8: Air of combustion for the fuel used in Juaben Oils Mills ……………………...66



APPENDIX 1: QUESTIONNAIRE TO JUABEN OILS MILLS

I. By-products characterization

1. What is the flow chart of the palm oil production?

2. What are the by-products of the palm oil processing? (Draw a cross in the box if yes)

Empty Fruit

Bunch Fibre Shell Cake Filtered Cakes

Palm Oil

Mills Effluent Others

3. What quantity of each by-product do you extracted?

Byproducts Quantity

Empty fruit bunches (EFB)

Fibers

Shell

Cake

Filtered Cakes

Effluent, sludge (POME)

Others

4. What are your current usages of each by-product?

Byproducts Uses


Fibers

Shell

Cake

Filtered Cakes


Others



5. What is the utilization rate of each by-product?

Byproducts Utilization rate


Fibers

Shell

Cake

Filtered Cakes


Others

6. What by-products don’t you use for energy purpose ? (Draw a cross in the box if yes)

Byproducts No used for energy


Cake

Filtered Cakes


Others

7. What constraints do you face while wanting to use them to produce energy?

Byproducts Constraints


Cake

Filtered Cakes


Others

8. What is the flow chart of shea oil production?

9. What are the by-products of the shea oil processing? (Shells, cake, filtered cake, others)

Shell Cake

Filtered Cakes Shea Oil Mill Effluent Others



10. What quantity of each by-product do you extracted?

Byproducts Quantity

Shell

Cake

Filtered Cakes

Effluent, sludge (SOME)

Others

11. What are your current usages of each by-product?

Byproducts Uses

Shell

Cake

Filtered Cakes


Others

12. What is the utilization rate of each by-product?

Byproducts Utilization rate

Shell

Cake

Filtered Cakes


Others

13. What by-products don’t you use for energy purpose?

Byproducts No used for energy

Cake

Filtered Cakes


Others



14. What constraints do you face while wanting to use them to produce energy?

Byproducts Constraints

Cake

Filtered Cakes


Others

II. Energetic aspects

1. Are the combustible dried or wet when you use them for the boiler?

2. What is the moisture content of the combustibles (fuel)?

Byproducts Moisture content


Fibre

Shell

Cake

Filtered Cake

Others

3. What is the calorific value of the combustibles (fuel)?

Byproducts CV(kJ/kg)


Fibers

Shell

Cake

Filtered Cake

Others

4. How many boilers do you have?

5. What are their types, dimensions and characteristics?

6. How many turbines do you have

7. What are their types, dimensions and characteristic (capacity)?

8. What is the pressure at exit?

55

Boiler

FFB reception Sterilization Stripping

Storage tank

Settling tank

Clarification

Oil dryer

Digestion

Fibre + Nuts

Pressing

Separation

Nuts Cracking

Clay bath

Drying Cooking

Pressing

Cracking

Filtration Storage tank

Crude PO

Reclaimed oil

Skimmed oil

Sludge

Sludge separator

POME

Dry oil

Settling pond

Fibre

Nuts

EFB

Fruits

Shell

Burning Ash for farms

Kernel + shell

Kernel

PKO cake

Crude PKO Clean PKO

Residues

Oil traditional recovery

Discharge

Oil traditional recovery

APPENDIX 2: OVERVIEW OF CRUDE PALM OIL (CPO) AND PALM KERNEL OIL (PKO) SECTIONS

56

Boiler

Shea seeds bags reception

Cleaner Cracker

Cooker

CSO

Pressing (Expeller)

Vibro-separator

Pressure leaf filter

Filtered oil tank

Storage tank

Cake

CSO

Cracked seeds

Filtered oil

Dried oil

Foots

Filtered Cake

Vacuum dryer

APPENDIX 3: OVERVIEW OF SHEA BUTTER SECTION


Thesis written by Félicien D. BADOU/37th Promotion 2iE- June 2008 57

APPENDIX 4: DAILY OVERVIEW OF CPO, PKO AND SB AND THE MILL CAPACITY

CRUDE PALM OIL DAYLY OVERVIEW

Month Date Shift Cages milled

Nut_imput (Mt)

Downtime (Hours)

Fulltime (Hours)

Capacity (Mt/h)

Average (Mt/h)

JUNE 07 19/06/2007 A 24 31.2 3.83 4.17 7.482 5.416 B 38 49.4 8 6.175 C 40 52 8 6.500 21/06/2007 A 24 31.2 8 3.900 B 28 36.4 1.83 6.17 5.900 C 28 36.4 8 4.550 27/06/2007 B 24 31.2 8 3.900 C 26 33.8 3 5 6.760 A 22 28.6 8 3.575

JULY 07 09/07/2007 A 36 46.8 14 3.343 3.377 C 40 52 14 3.714 16/07/2007 C 28 36.4 1.54 12.46 2.921 A 38 49.4 14 3.529 23/07/2007 A 16 20.8

AUGUST 07 03/08/2007 C 8 10.4 6 8 1.300 2.177 A 0 0 5 9 0.000 13/08/2007 C 22 28.6 14 2.043 A 24 31.2 2.5 11.5 2.713 27/08/2007 C 20 26 14 1.857 A 32 41.6 14 2.971

SEPTEMBER 07

06/09/2007 A 42 54.6 14 3.900 2.897

C 34 44.2 14 3.157 11/09/2007 C 36 46.8 14 3.343 A 26 33.8 14 2.414 26/09/2007 C 18 23.4 14 1.671

OCTOBER 07

05/10/2007 B 32 41.6 14 2.971 2.043

16/10/2007 A 28 36.4 14 2.600 22/10/2007 A 6 7.8 14 0.557

NOVEMBER 07

07/11/2007 A 10 13 14 0.929 0.929

16/11/2007 A 6 7.8 14 0.557 28/11/2007 A 14 18.2 14 1.300

DECEMBER 07

06/12/2007 A 8 10.4 14 0.743 0.774

14/12/2007 A 10 13 14 0.929 20/12/2007 A 7 9.1 14 0.650

JANUARY 08

07/01/2008 A 8 10.4 14 0.743 0.867

15/01/2008 A 8 10.4 14 0.743 23/01/2008 A 12 15.6 14 1.114

FEBRUARY 08

07/02/2008 B 8 10.4 14 0.743 1.811

12/02/2008 A 24 31.2 14 2.229 27/02/2008 A 28 36.4 14 2.600 B 18 23.4 14 1.671



MARCH 08 04/03/2008 B 10 13 14 0.929 3.735 A 28 36.4 14 2.600 13/03/2008 A 34 44.2 2 12 3.683 B 23 29.9 3 11 2.718 25/03/2008 C 28 36.4 3.5 4.5 8.089 A 22 28.6 8 3.575 B 28 36.4 8 4.550

APRIL 08 02/04/2008 A 45 58.5 1 7 8.357 6.945 B 39 50.7 8 6.338 C 46 59.8 8 7.475 10/04/2008 A 30 39 8 4.875 C 23 29.9 4 4 7.475 B 33 42.9 2 6 7.150 28/04/2008 B 28 36.4 2 6 6.067 C 39 50.7 8 6.338 A 42 54.6 1 7 7.800

MAY 08 10/05/2008 C 37 48.1 8 6.013 6.671 A 29 37.7 2.170 5.83 6.467 11/05/2008 38 49.4 0.750 7.25 6.814 B 38 49.4 8 6.175 C 37 48.1 1.750 6.25 7.696 12/05/2008 A 40 52 0.420 7.58 6.860

Average of the mill capacity per period (Mt/h) Peak season 6.344 Mid season 2.846 Lean season 1.095

PALM KERNEL OIL DAYLY OVERVIEW

Peak season Mid

season Lean season

MONTH DATE SHIFT Bags milled

Nut_imput (kg)

Downtime (Hours)

Fulltime (Hours)

Capacity (kg/h)

Average (kg/h)

JANUARY 08

week 3(14-20) 56.57 3960 98.8 69.2 57.22543353 62.0252935

FEBRUARY 08

average of weeks 62.24 4357 102.8 65.2 66.82515337

MARCH 08 05/03/2008 A&B 20 1400 16 87.5 161.458333

10/03/2008 B&C 45 3150 16 196.875

26/03/2008 B&C 40 2800 2 14 200

APRIL 08 03/04/2008 A&B&C 81 5670 1 23 246.5217391 257.303423

15/04/2008 A&B&C 90 6300 0.5 23.5 268.0851064

Average of the mill capacity per period (kg/h) Peak season 257.303

Mid season 161.458

Lean season 62.025 Note: For the colour, the red is chosen for the peak period, the yellow for the mean period and the grey for the trough period.



SHEA BUTTER DAYLY OVERVIEW

MONTH DATE SHIFT Bags milled

Nut_imput (Mt)

Downtime (Hours)

Fulltime (Hours)

Capacity (Mt/h)

FEBRUARY 08

29/02/2008 A&B&C 344 26.66 24 1.110833333

MARCH 08 03/03/2008 A&B&C 285 22.0875 24 0.9203125

12/03/2008 A&B&C 154 11.935 10.5 13.5 0.884074074

25/03/2008 A&B&C 356 27.59 2 22 1.254090909

APRIL 08 01/04/2008 A&B&C 224 17.36 2 22 0.789090909

08/04/2008 A&B&C 293 22.7075 7.67 16.33 1.390538885

14/04/2008 A&B&C 318 24.645 24 1.026875

28/04/2008 A&B&C 288 22.32 7 17 1.312941176

MAY 08 01/05/2008 A&B&C 464 35.96 0 24 1.498333333

03/05/2008 A&B 265 20.5375 6.83 17.17 1.196126966

Average of the mill capacity per period (Mt/h)

Average 1.138

MILL CAPACITY

Peak season Mean season Lean season Total

CPO section (Mt/h) 6.344 2.846 1.095

PKO section (Mt/h) 0.257 0.161 0.062

SB section (Mt/h) 1.138 1.138 1.138

Total capacity (Mt/h) 7.740 4.146 2.295

Number of hours 1800 2500 1440

Periodic capacity of CPO (Mt) 11419 7115 1577 20111

Overall capacity (Mt) 13931 10364 3305 27601



APPENDIX 5: HIGH CALORIFIC VALUE (HCV) AND MOISTURE CONTENT

FIBRE SHELL Sample Ti Tf HCV (kJ/kg) Sample Ti Tf HCV (kJ/kg)

F11 29.6 30.5 15562.8 S11 26.6 27.8 20750.4 F12 31 32.05 18156.6 S12 F13 27.7 28.8 19021.2 S13 33.4 34.3 15562.8 F1 18588.9 S1 20750.4 F21 29 30.15 19885.8 S21 33.45 34.55 19021.2 F22 32.2 33.3 19021.2 S22 34.1 35.15 18156.6 F23 34.55 35.65 19021.2 S23 33.1 34.15 18156.6 F2 19309.4 S2 18444.8 F31 26.6 27.7 19021.2 S31 30.2 31.3 19021.2 F32 32.3 33.3 17292 S32 31.2 32.3 19021.2 F33 35.4 36.35 16427.4 S33 32.15 33.2 18156.6 F3 18156.6 S3 18733 F41 36.3 37.3 17292 S41 33.38 34.48 19021.2 F42 30.3 31.45 19885.8 S42 34.6 35.68 18675.36 F43 34.1 35.15 18156.6 S43 36.1 37.1 17292 F4 18444.8 S4 18848.28

Average 18624.93 Average 19194.12

CAKE FILTERED CAKE Sample Ti Tf HCV (kJ/kg) Sample Ti Tf HCV (kJ/kg)

C11 28.3 29.7 24208.8 FC11 27.8 29.6 31125.6 C12 30.8 32 20750.4 FC12 32.9 34.4 25938 C13 32.8 33.5 12104.4 FC13 33.6 35.1 25938 C1 22479.6 FC1 25938 C21 31.2 32.2 17292 FC21 30.3 31.8 25938 C22 33 34 17292 FC22 29.5 31 25938 C23 32.7 33.6 15562.8 FC23 31.7 33.4 29396.4 C2 17292 FC2 27090.8 C31 31.7 32.78 18675.36 FC31 34.3 35.85 26802.6 C32 27.6 28.7 19021.2 FC32 33 34.5 25938 C33 FC33 35.8 37.1 22479.6 C3 18848.28 FC3 25073.4 C41 36.6 37.6 17292 FC41 32.6 33.7 19021.2 C42 35.05 36.1 18156.6 FC42 36.6 37.95 23344.2 C43 29.1 30.4 22479.6 FC43 31.1 32.65 26802.6 C4 19309.4 FC4 25073.4

Average 19482.32 Average 25793.9

EFB EFB EFB31 29.7 30.8 19021.2

Sample Ti Tf HCV (kJ/kg) EFB32 30.65 31.7 18156.6 EFB11 29.8 30.78 16946.16 EFB33 33.9 34.9 17292 EFB12 31.35 32.2 14698.2 EFB3 18156.6 EFB13 32.6 33.5 15562.8 EFB41 35.2 36.05 14698.2 EFB1 16254.48 EFB42 29.9 30.9 17292 EFB21 30.1 31.1 17292 EFB43 30.45 31.48 17810.76 EFB22 29 30.05 18156.6 EFB4 17551.38 EFB23 30.45 31.5 18156.6 EFB2 17868.4 Average 17457.715



FIBRE

Date Basin Basin (g) (B +S)(g) Sample (DB+S)1

(g) ML1 (g)

(DB+S)2 (g)

ML 2 (g)

(DB+S)3 (g)

ML3 (g) Total ML (g) M content

(%)

16/04/2008 A 49.61 57.87 8.26 55.11 2.76 55.11 0 55.11 0 2.76 33.41 16/04/2008 B 46.09 60.96 14.87 54.82 6.14 54.82 0 54.82 0 6.14 41.29 23/04/2008 A 46.1 52.15 6.05 50.25 1.9 50.25 0 50.25 0 1.9 31.40 23/04/2008 B 49.45 56.95 7.5 54.5 2.45 54.5 0 54.5 0 2.45 32.67 07/05/2008 A 45.85 54.8 8.95 53.05 1.75 53.05 0 53.05 0 1.75 19.55 07/05/2008 B 46 58.05 12.05 55.75 2.3 55.75 0 55.75 0 2.3 19.09

AVERAGE 32

SHELL


(g) ML1 (g) (DB+S)2

(g) ML 2 (g)

(DB+S)3 (g) ML3 (g) Total ML (g)

M content (%)

18/04/2008 A 32.1 60.3 28.2 56.05 4.25 56.05 0 56.05 0 4.25 15.07 18/04/2008 B 33.95 65.05 31.1 60.3 4.75 60.15 0.15 60.1 0.05 4.95 15.92 23/04/2008 A 32.1 62.35 30.25 57.6 4.75 57.55 0.05 57.55 0 4.8 15.87 23/04/2008 B 45.8 83.8 38 77.85 5.95 77.8 0.05 77.8 0 6 15.79 07/05/2008 A 50.9 90.95 40.05 83.2 7.75 82.85 0.35 82.8 0.05 8.15 20.35 07/05/2008 B 49.4 87.6 38.2 79.85 7.75 79.8 0.05 79.75 0.05 7.85 20.55

AVERAGE 17

CAKE


(g) ML1 (g) (DB+S)2

(g) ML 2 (g)

(DB+S)3 (g) ML3 (g) Total ML (g)

M content (%)

16/04/2008 A 32.2 65.42 33.22 63.87 1.55 63.84 0.03 63.84 0 1.58 4.76 16/04/2008 B 46.25 82.23 35.98 80.77 1.46 80.77 0 80.77 0 1.46 4.06 23/04/2008 A 50.8 75.55 24.75 69.45 6.1 69.45 0 69.45 0 6.1 24.65 23/04/2008 B 49.35 75.3 25.95 69.2 6.1 69.2 0 69.2 0 6.1 23.51 07/05/2008 A 46.1 81.95 35.85 72.5 9.45 72.45 0.05 72.45 0 9.5 26.50 07/05/2008 B 49.4 88.2 38.8 79.05 9.15 78.85 0.2 78.85 0 9.35 24.10

AVERAGE 25



FILTERED CAKE


(g) ML1 (g)

(DB+S)2 (g)

ML 2 (g)

(DB+S)3 (g)


(%)

16/04/2008 A 45.98 88.28 42.3 86.67 1.61 86.54 0.13 86.53 0.01 1.75 4.14 16/04/2008 B 51.01 97.96 46.95 96.17 1.79 96.02 0.15 95.98 0.04 1.98 4.22 23/04/2008 A 45.9 79.15 33.25 77.75 1.4 77.7 0.05 77.7 0 1.45 4.36 23/04/2008 B 50.4 81.5 31.1 80.25 1.25 80.25 0 80.25 0 1.25 4.02 07/05/2008 A 32.15 75.6 43.45 74.35 1.25 74.25 0.1 74.25 0 1.35 3.11 07/05/2008 B 35.45 77.45 42 75.95 1.5 75.85 0.1 75.85 0 1.6 3.81

AVERAGE 4

EMPTY FRUIT BUNCH


(g) ML1 (g)

(DB+S)2 (g)

ML 2 (g)

(DB+S)3 (g)


(%)

18/04/2008 A 46.1 63 16.9 52.55 10.45 52.55 0 52.55 0 10.45 61.83 18/04/2008 B 49.5 66.2 16.7 56.55 9.65 55.6 0.95 55.35 0.25 10.85 64.97 23/04/2008 A 33.95 42.15 8.2 37.45 4.7 37.4 0.05 37.4 0 4.75 57.93

AVERAGE 62

Note: In this Appendix 5, the grey colour is for the box not utilized for the computations since there are not close to the others values. Abbreviations: B: Basin/ S: Sample/ DB: Dried Basin/ ML: Moisture Loss/ M content: Moisture Content



APPENDIX 6: PARAMETERS OF PALM OIL MILL EFFLUENT (POME)

TEMPERATURE Entrance of the pond Exit of the pond

Date N° Temperature Temperature 15/04/2008 1:00 PM 53.3 51.9 16/04/2008 1:00 PM 57.4 55.5 21/04/2008 2:00 PM 67.1 56.5 23/04/2008 1:00 PM 71.3 60.2 29/04/2008 9:00 AM 64.3 55.2 13/05/2008 9:00 AM 57 56 15/05/2008 8:30 AM 60 60

Average of temperature 61.5 56.5

pH

Date Entrance of the pond Exit of the pond 4.84 5.15

30/04/2008 4.29 4.5 08/05/2008 5.64 5.11 13/05/2008 4.67 5.08 15/05/2008 4.84

Average of pH 4.86 4.94

COD

Normality 0.0951 Volume of sample (ml) 10

Date Blank Entrance of the pond Exit of the pond Dilution factor

30/04/2008 26.8 15.2 20.5 100

COD (mg/l) 88252.8 47930.4

14/05/2008 21.4 18.5 20.8 100

COD (mg/l) 22063.2 4564.8

16/05/2008 25.8 24.8 21.7 200

COD (mg/l) 15216 62385.6

21/05/2008 27.75 22.9 200

COD (mg/l) 73797.6

Average of COD (mg/l) 41844 47169.6

BOD Date Blank Entrance of the pond Exit of the pond Dilution factor

02/05/2008 BOD1 8.7 8.2 8.3 100 08/05/2008 BOD5 7.9 8.1 200

BOD (mg/l) 6000 4000 14/05/2008 BOD1 9.3 7.9 8.2 500 19/05/2008 BOD5 0 1.4

BOD (mg/l) 3950 3400 16/05/2008 BOD1 9.3 8.3 8.4 500 21/05/2008 BOD5 0.3 0.45

BOD (mg/l) 4000 3975 21/05/2008 BOD1 11.05 10.5 100 26/05/2008 BOD5 10.5 10.15 200

BOD (mg/l) 7000



APPENDIX 7: CONSUMPTION OF FUEL DURING THE PEAK SEASON

CAKE

Date Gross

Weight (Mt) Tare Weight

(Mt) Sample (Mt) Start End

22/04/2008 5.73 3.66 2.07 10:45 AM 4:15 PM

24/04/2008 5.49 3.67 1.82 11:10 AM 9:50 PM

SHELL

Date Gross

Weight (Mt) Tare Weight

(Mt) Sample (Mt) Start End

22/04/2008 5.49 3.66 1.83 10:45 AM 4:15 PM

24/04/2008 5.62 3.67 1.95 11:10 AM 9:50 PM

FIBRE

Date Cages milled

Fibre rate/cage (Mt)

Sample (Mt) Start End

22/04/2008 22 0.156 3.432 10:45 AM 4:15 PM

24/04/2008 58 0.156 9.048 11:10 AM 9:50 PM

FUEL

Date Total of Sample

(Mt) Length of Utilization

(Hours) Utilization Rate

(Mt/h)

22/04/2008 7.332 5.50 1.333090909

24/04/2008 12.818 10.67 1.20131209

Average 1.3

SURVEY OF FUEL CONSUMPTION DURING THE PEAK PERIOD

Quantity (Mt/h) LHV (kJ/kg) Energy (GJ/h)

Fuel consumed 1.3

Fibre (50%) 0.65 12665 8.23

Shell (20%) 0.26 15931 4.14

Cake (20%) 0.26 14612 3.80

Filtered cake (10%) 0.13 25794 3.35

Consumption (GJ/h) 19.53



APPENDIX 8: AIR OF COMBUSTION FOR THE FUEL USED IN JUABEN OILS MILLS

FLOW OF AIR IN JOM Month Wind speed (m/s) Periodic average (m/s) Air inlet surface (m2) Air flow (kg/s)

January 1.1 Lean season Lean season

February 1.5 1.2 0.72 1.1

March 1.6

April 1.8 Peak season Peak season

May 1.6 1.7 1.6

June 1.6

July 1.9

August 2 Mid season Mid season

September 1.6 1.7 1.6

October 1.4

November 1.1

December 1

AMOUNT OF AIR REQUIRED

Peak season Mid season Lean season Bulk of fuel (kg/h)

(Fibre, ,Shell,,Cake and Fil Cake) 2038.0 1303.4 935.7

Consumption of fuel (kg/s) 0.6 0.4 0.3

Air required (kg/s) 4.6 2.9 2.1



ABSTRACT

The International Community in its endeavour to assure the sustainable development leans

more and more towards the renewable energies such as the solar energy, wind energy,

geothermal energy and mainly biomass. Some bio-fuels, biogases as well as electricity and

thermal energy can be produced while using biomass. This study fits such context and aims to

propose some optimal methods for the Cogeneration of heat and electricity from the waste of a

food industry. It took place in Juaben Oils Mill (JOM), an oil mill of Kumasi suburbs which

processes every year 20,111 Mt of Fresh Fruit Bunch (FFB) from palm oil tree; 1,307 Mt of

palm kernel (PK) and 6,453 Mt of shea seeds. From the process of Crude Palm Oil (CPO),

Empty Fruit Bunch (EFB), fibre, shell and the Palm Oil Mill Effluent (POME) are extracted. All

these residues can act as fuel to generate steam and power. The milling of shea oil gives also

some very good combustibles i.e. the Shea cake and the Shea Filtered Cake. The issues of the

study show that while utilizing the by-products aforementioned, it is possible to meet very

largely the energetic requirements of the mill (some2.75 GWh and 24,464 Mt of steam per year).

And therefore to use the surplus of fuel to produce electricity that will be sold to Electricity

Company of Ghana (ECG). Indeed, an efficient utilization of the 8,274 Mt of residues currently

combusted there (fibre, shell, cake and filtered cake) that is to say the harmonization of the

amount of fuel required per hour with the quantity of air of combustion will permit at once to

assure the energetic self sufficiency of the mill and to save some 1.5 GWh per year.

Besides, with the 4,626 Mt of EFB available every year some 2.73 GWh could be generated if

the mill consents to split and dewater them. This option will also help to recover about 70.4 Mt

of residual oil and some 100.6 Mt of ash for land application.

Furthermore, the volume of POME (some 10,558 m3) resulting from the production of CPO will

permit to generate about 0.44 GWh per year thanks to biomethanation followed by Cogeneration.

One other benefit linked to such practice is the possibility to collect the treated effluent in order

to water more than 30 hectares of palm oil plantation of which the yield should be enhance

around 10 to 23 %.

On the whole thanks to cogeneration, the by-products of this Oils mill will help it to be self

sufficient on an energetic view and to get a surplus of 4.67 GWh per year.

Key words: Biomass, Cogeneration, food industry, residues, optimal methods.



RESUME

La Communauté Internationale dans sa tentative à assurer le développement durable

penche de plus en plus vers les énergies renouvelables dont le solaire, l’éolien, la géothermique

et surtout la biomasse. Des biocarburants, des biogaz ainsi que de l’électricité et de l’énergie

thermique peuvent être produits à partir de la biomasse. C’est dans ce canevas que s’inscrit la

présente étude dont l’enjeu est de proposer des méthodes optimales de cogénération de la chaleur

et de l’électricité à partir des déchets d’une industrie agroalimentaire. Elle s’est déroulée à

Juaben Oils Mills (JOM), une huilerie de la banlieue de Kumasi qui transforme chaque année

20111 tonnes de régimes de palmier à huile et 6453 tonnes de fruits de karité. De la production

de l’huile de palme brute, le régime vide, la fibre, la coque et les effluents de l’huilerie sont

extraits. Tous ces résidus peuvent servir de combustibles pour générer de la vapeur et de

l’électricité. La transformation de fruits de karité en huile fournit elle aussi de très bons

combustibles dont un semi-produit huileux et un résidu moins huileux. Les résultats obtenus

révèlent qu’en utilisant les résidus susmentionnés il est possible de couvrir très largement les

besoins énergétiques de cette agro-industrie (2,75 GWh et 24464 tonnes de vapeur). Et ainsi

donc d’utiliser le surplus de combustibles pour produire de l’électricité qui sera vendu à la

Compagnie Electrique du Ghana. En effet, une utilisation efficiente des 8274 tonnes de résidus

annuellement comburées dans l’huilerie (fibres, coques et les résidus de karité) c'est-à-dire

l’harmonisation de la quantité de combustible requise par heure avec celle d’air de combustion

permettra à la fois d’assurer l’autosuffisance énergétique et d’économiser 1,5 GWh par an. De

plus avec les 4626 tonnes de régimes vidés de fruits disponibles chaque année, 2,73 GWh pourra

être généré si l’industrie consent à les pré traiter. Cette option permettra aussi de récupérer

environ 70,4 tonnes d’huile résiduelle et 100,6 tonnes de cendres pour l’amendement des

plantations. En outre, le volume d’effluents (10558 m3) résultant de la production d’huile de

palme brute pourra permettre de produire environ 0.44 GWh par an grâce à la bio-méthanisation

suivie de la Cogénération. Un autre avantage lié à une telle pratique c’est la possibilité de

collecter les effluents traités pour irriguer environ 30 hectares de palmiers dont les rendements

pourront augmenter de 10 à 23 %.

Au total, avec la cogénération cette huilerie pourra de dégager un surplus de 4,67 GWh par an.

Mots clés : Biomasse, Cogénération, industrie agroalimentaire, résidus, méthodes optimales.

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